Multi-layer, multi-material micro-scale and millimeter-scale devices with enhanced electrical and/or mechanical properties

ABSTRACT

Some embodiments of the invention are directed to electrochemical fabrication methods for forming structures or devices (e.g. microprobes for use in die level testing of semiconductor devices) from a core material and a shell or coating material that partially coats the surface of the structure. Other embodiments are directed to electrochemical fabrication methods for producing structures or devices (e.g. microprobes) from a core material and a shell or coating material that completely coats the surface of each layer from which the probe is formed including interlayer regions. Additional embodiments of the invention are directed to electrochemical fabrication methods for forming structures or devices (e.g. microprobes) from a core material and a shell or coating material wherein the coating material is located around each layer of the structure without locating the coating material in inter-layer regions.

RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.14/986,500, filed Dec. 31, 2015, which is a continuation of U.S. patentapplication Ser. No. 14/017,535, filed Sep. 4, 2013, now U.S. Pat. No.9,671,429, issued on Jun. 6, 2017, and which also is acontinuation-in-part of U.S. patent application Ser. No. 12/431,680,filed Apr. 28, 2009, now U.S. Pat. No. 9,244,101, issued on Jan. 26,2016. The '535 application is a continuation of U.S. patent applicationSer. No. 12/906,970, filed Oct. 18, 2010, now U.S. Pat. No. 8,613,846,issued on Dec. 24, 2013, which claims benefit of U.S. Provisional PatentApplication No. 61/252,633, filed Oct. 16, 2009. The '970 application isa continuation-in-part of U.S. patent application Ser. No. 12/431,680,filed Apr. 28, 2009, now U.S. Pat. No. 9,244,101, issued on Jan. 26,2016. The '680 application is a continuation of U.S. patent applicationSer. No. 11/029,221, filed Jan. 3, 2005, now U.S. Pat. No. 7,531,077,issued on May 12, 2009, which claims benefit of U.S. Provisional PatentApplication Nos. 60/533,897, 60/533,975, 60/533,947, 60/533,948, eachfiled on Dec. 31, 2003; and of 60/540,510, filed Jan. 29, 2004. Each ofthese applications, including any appendices attached thereto, with theexception of U.S. patent application Ser. No. 11/029,221 is incorporatedherein by reference as if set forth in full herein.

Furthermore, the following U.S. Patent Applications are incorporatedherein by reference as if set forth in full: U.S. patent applicationSer. No. 11/139,262, filed May 26, 2005; U.S. Patent Application No.60/574,733, filed May 26, 2004; U.S. Patent Application No. 60/468,979,filed May 7, 2003; U.S. Patent Application No. 60/469,053, filed May 7,2003; and U.S. Patent Application No. 60/533,891, filed Dec. 31, 2003.

FIELD OF THE INVENTION

The present invention relates generally to the field of ElectrochemicalFabrication and the associated formation of three-dimensional structures(e.g. microscale or millimeter scale structures). In particular, someembodiments are focused on the electrochemical fabrication ofmultilayer, multi-material devices (e.g. probe elements for use ascompliant electronic contact elements) that are configured to haveimproved properties (e.g. electrical properties, thermal properties,and/or mechanical properties).

BACKGROUND OF THE INVENTION

An electrochemical fabrication technique for forming three-dimensionalstructures from a plurality of adhered layers is being commerciallypursued by Microfabrica® Inc. (formerly MEMGen Corporation) of Van Nuys,Calif. under the name EFAB®.

Various electrochemical fabrication techniques were described in U.S.Pat. No. 6,027,630, issued on Feb. 22, 2000 to Adam Cohen. Someembodiments of this electrochemical fabrication technique allow theselective deposition of a material using a mask that includes apatterned conformable material on a support structure that isindependent of the substrate onto which plating will occur. Whendesiring to perform an electrodeposition using the mask, the conformableportion of the mask is brought into contact with a substrate, but notadhered or bonded to the substrate, while in the presence of a platingsolution such that the contact of the conformable portion of the mask tothe substrate inhibits deposition at selected locations. Forconvenience, these masks might be generically called conformable contactmasks; the masking technique may be generically called a conformablecontact mask plating process. More specifically, in the terminology ofMicrofabrica Inc. such masks have come to be known as INSTANT MASKS™ andthe process known as INSTANT MASKING™ or INSTANT MASK™ plating.Selective depositions using conformable contact mask plating may be usedto form single selective deposits of material or may be used in aprocess to form multi-layer structures. The teachings of the '630 patentare hereby incorporated herein by reference as if set forth in fullherein. Since the filing of the patent application that led to the abovenoted patent, various papers about conformable contact mask plating(i.e. INSTANT MASKING) and electrochemical fabrication have beenpublished:

-   (1) A. Cohen, G. Zhang, F. Tseng, F. Mansfeld, U. Frodis and P.    Will, “EFAB: Batch production of functional, fully-dense metal parts    with micro-scale features”, Proc. 9th Solid Freeform Fabrication,    The University of Texas at Austin, p 161, August 1998.-   (2) A. Cohen, G. Zhang, F. Tseng, F. Mansfeld, U. Frodis and P.    Will, “EFAB: Rapid, Low-Cost Desktop Micromachining of High Aspect    Ratio True 3-D MEMS”, Proc. 12th IEEE Micro Electro Mechanical    Systems Workshop, IEEE, p 244, January 1999.-   (3) A. Cohen, “3-D Micromachining by Electrochemical Fabrication”,    Micromachine Devices, March 1999.-   (4) G. Zhang, A. Cohen, U. Frodis, F. Tseng, F. Mansfeld, and P.    Will, “EFAB: Rapid Desktop Manufacturing of True 3-D    Microstructures”, Proc. 2nd International Conference on Integrated    MicroNanotechnology for Space Applications, The Aerospace Co., April    1999.-   (5) F. Tseng, U. Frodis, G. Zhang, A. Cohen, F. Mansfeld, and P.    Will, “EFAB: High Aspect Ratio, Arbitrary 3-D Metal Microstructures    using a Low-Cost Automated Batch Process”, 3rd International    Workshop on High Aspect Ratio MicroStructure Technology (HARMST'99),    June 1999.-   (6) A. Cohen, U. Frodis, F. Tseng, G. Zhang, F. Mansfeld, and P.    Will, “EFAB: Low-Cost, Automated Electrochemical Batch Fabrication    of Arbitrary 3-D Microstructures”, Micromachining and    Microfabrication Process Technology, SPIE 1999 Symposium on    Micromachining and Microfabrication, September 1999.-   (7) F. Tseng, G. Zhang, U. Frodis, A. Cohen, F. Mansfeld, and P.    Will, “EFAB: High Aspect Ratio, Arbitrary 3-D Metal Microstructures    using a Low-Cost Automated Batch Process”, MEMS Symposium, ASME 1999    International Mechanical Engineering Congress and Exposition,    November, 1999.-   (8) A. Cohen, “Electrochemical Fabrication (EFAB™)”, Chapter 19 of    The MEMS Handbook, edited by Mohamed Gad-El-Hak, CRC Press, 2002.-   (9) Microfabrication—Rapid Prototyping's Killer Application”, pages    1-5 of the Rapid Prototyping Report, CAD/CAM Publishing, Inc., June    1999.

The disclosures of these nine publications are hereby incorporatedherein by reference as if set forth in full herein.

An electrochemical deposition process for forming multilayer structuresmay be carried out in a number of different ways as set forth in theabove patent and publications. In one form, this process involves theexecution of three separate operations during the formation of eachlayer of the structure that is to be formed:

1. Selectively depositing at least one material by electrodepositionupon one or more desired regions of a substrate. Typically this materialis either a structural material or a sacrificial material.

2. Then, blanket depositing at least one additional material byelectrodeposition so that the additional deposit covers both the regionsthat were previously selectively deposited onto, and the regions of thesubstrate that did not receive any previously applied selectivedepositions. Typically this material is the other of a structuralmaterial or a sacrificial material.

3. Finally, planarizing the materials deposited during the first andsecond operations to produce a smoothed surface of a first layer ofdesired thickness having at least one region containing the at least onematerial and at least one region containing at least the one additionalmaterial.

After formation of the first layer, one or more additional layers may beformed adjacent to an immediately preceding layer and adhered to thesmoothed surface of that preceding layer. These additional layers areformed by repeating the first through third operations one or more timeswherein the formation of each subsequent layer treats the previouslyformed layers and the initial substrate as a new and thickeningsubstrate.

Once the formation of all layers has been completed, at least a portionof at least one of the materials deposited is generally removed by anetching process to expose or release the three-dimensional structurethat was intended to be formed. The removed material is a sacrificialmaterial while the material that forms part of the desired structure isa structural material.

One method of performing the selective electrodeposition involved in thefirst operation is by conformable contact mask plating. In this type ofplating, one or more conformable contact (CC) masks are first formed.The CC masks include a support structure onto which a patternedconformable dielectric material is adhered or formed. The conformablematerial for each mask is shaped in accordance with a particularcross-section of material to be plated (the pattern of conformablematerial is complementary to the pattern of material to be deposited).In such a process, at least one CC mask is used for each uniquecross-sectional pattern that is to be plated.

The support for a CC mask may be a plate-like structure formed of ametal that is to be selectively electroplated and from which material tobe plated will be dissolved. In this typical approach, the support willact as an anode in an electroplating process. In an alternativeapproach, the support may instead be a porous or otherwise perforatedmaterial through which deposition material will pass during anelectroplating operation on its way from a distal anode to a depositionsurface. In either approach, it is possible for multiple CC masks toshare a common support, i.e. the patterns of conformable dielectricmaterial for plating multiple layers of material may be located indifferent areas of a single support structure. When a single supportstructure contains multiple plating patterns, the entire structure isreferred to as the CC mask while the individual plating masks may bereferred to as “submasks”. In the present application such a distinctionwill be made only when relevant to a specific point being made.

In preparation for performing the selective deposition of the firstoperation, the conformable portion of the CC mask is placed inregistration with and pressed against a selected portion of (1) thesubstrate, (2) a previously formed layer, or (3) a previously depositedmaterial forming a portion of a layer that is being formed. The pressingtogether of the CC mask and relevant substrate, layer, or materialoccurs occur in such a way that all openings, in the conformableportions of the CC mask contain plating solution. The conformablematerial of the CC mask that contacts the substrate, layer, or materialacts as a barrier to electrodeposition while the openings in the CC maskthat are filled with electroplating solution act as pathways fortransferring material from an anode (e.g. the CC mask support) to thenon-contacted portions of the substrate (which act as a cathode duringthe plating operation) when an appropriate potential and/or current aresupplied.

An example of a CC mask and CC mask plating are shown in FIGS. 1A-1C.FIG. 1A shows a side view of a CC mask 8 consisting of a conformable ordeformable (e.g. elastomeric) insulator 10 patterned on an anode 12. Theanode has two functions. One is as a supporting material for thepatterned insulator 10 to maintain its integrity and alignment since thepattern may be topologically complex (e.g., involving isolated “islands”of insulator material). The other function is as an anode for theelectroplating operation. FIG. 1A also depicts a substrate 6, separatedfrom mask 8, onto which material will be deposited during the process offorming a layer. CC mask plating selectively deposits material 22 ontosubstrate 6 by simply pressing the insulator against the substrate thenelectrodepositing material through apertures 26 a and 26 b in theinsulator as shown in FIG. 1B. After deposition, the CC mask isseparated, preferably non-destructively, from the substrate 6 as shownin FIG. 10.

The CC mask plating process is distinct from a “through-mask” platingprocess in that in a through-mask plating process the separation of themasking material from the substrate would occur destructively.Furthermore in a through mask plating process, openings in the maskingmaterial are typically formed while the masking material is in contactwith and adhered to the substrate. As with through-mask plating, CC maskplating deposits material selectively and simultaneously over the entirelayer. The plated region may consist of one or more isolated platingregions where these isolated plating regions may belong to a singlestructure that is being formed or may belong to multiple structures thatare being formed simultaneously. In CC mask plating as individual masksare not intentionally destroyed in the removal process, they may beusable in multiple plating operations.

Another example of a CC mask and CC mask plating is shown in FIGS.1D-1G. FIG. 1D shows an anode 12′ separated from a mask 8′ that includesa patterned conformable material 10′ and a support structure 20. FIG. 1Dalso depicts substrate 6 separated from the mask 8′. FIG. 1E illustratesthe mask 8′ being brought into contact with the substrate 6. FIG. 1Fillustrates the deposit 22′ that results from conducting a current fromthe anode 12′ to the substrate 6. FIG. 1G illustrates the deposit 22′ onsubstrate 6 after separation from mask 8′. In this example, anappropriate electrolyte is located between the substrate 6 and the anode12′ and a current of ions coming from one or both of the solution andthe anode are conducted through the opening in the mask to the substratewhere material is deposited. This type of mask may be referred to as ananodeless INSTANT MASK™ (AIM) or as an anodeless conformable contact(ACC) mask.

Unlike through-mask plating, CC mask plating allows CC masks to beformed completely separate from the substrate on which plating is tooccur (e.g. separate from a three-dimensional (3D) structure that isbeing formed). CC masks may be formed in a variety of ways, for example,using a photolithographic process. All masks can be generatedsimultaneously, e.g. prior to structure fabrication rather than duringit. This separation makes possible a simple, low-cost, automated,self-contained, and internally-clean “desktop factory” that can beinstalled almost anywhere to fabricate 3D structures, leaving anyrequired clean room processes, such as photolithography to be performedby service bureaus or the like.

An example of the electrochemical fabrication process discussed above isillustrated in FIGS. 2A-2F. These figures show that the process involvesdeposition of a first material 2 which is a sacrificial material and asecond material 4 which is a structural material. The CC mask 8, in thisexample, includes a patterned conformable material (e.g. an elastomericdielectric material) 10 and a support 12 which is made from depositionmaterial 2. The conformal portion of the CC mask is pressed againstsubstrate 6 with a plating solution 14 located within the openings 16 inthe conformable material 10. An electric current, from power supply 18,is then passed through the plating solution 14 via (a) support 12 whichdoubles as an anode and (b) substrate 6 which doubles as a cathode. FIG.2A illustrates that the passing of current causes material 2 within theplating solution and material 2 from the anode 12 to be selectivelytransferred to and plated on the substrate 6. After electroplating thefirst deposition material 2 onto the substrate 6 using CC mask 8, the CCmask 8 is removed as shown in FIG. 2B. FIG. 2C depicts the seconddeposition material 4 as having been blanket-deposited (i.e.non-selectively deposited) over the previously deposited firstdeposition material 2 as well as over the other portions of thesubstrate 6. The blanket deposition occurs by electroplating from ananode (not shown), composed of the second material, through anappropriate plating solution (not shown), and to the cathode/substrate6. The entire two-material layer is then planarized to achieve precisethickness and flatness as shown in FIG. 2D. After repetition of thisprocess for all layers, the multi-layer structure 20 formed of thesecond material 4 (i.e. structural material) is embedded in firstmaterial 2 (i.e. sacrificial material) as shown in FIG. 2E. The embeddedstructure is etched to yield the desired device, i.e. structure 20, asshown in FIG. 2F.

Various components of an exemplary manual electrochemical fabricationsystem 32 are shown in FIGS. 3A-3C. The system 32 consists of severalsubsystems 34, 36, 38, and 40. The substrate holding subsystem 34 isdepicted in the upper portions of each of FIGS. 3A-3C and includesseveral components: (1) a carrier 48, (2) a metal substrate 6 onto whichthe layers are deposited, and (3) a linear slide 42 capable of movingthe substrate 6 up and down relative to the carrier 48 in response todrive force from actuator 44. Subsystem 34 also includes an indicator 46for measuring differences in vertical position of the substrate whichmay be used in setting or determining layer thicknesses and/ordeposition thicknesses. The subsystem 34 further includes feet 68 forcarrier 48 which can be precisely mounted on subsystem 36.

The CC mask subsystem 36 shown in the lower portion of FIG. 3A includesseveral components: (1) a CC mask 8 that is actually made up of a numberof CC masks (i.e. submasks) that share a common support/anode 12, (2)precision X-stage 54, (3) precision Y-stage 56, (4) frame 72 on whichthe feet 68 of subsystem 34 can mount, and (5) a tank 58 for containingthe electrolyte 16. Subsystems 34 and 36 also include appropriateelectrical connections (not shown) for connecting to an appropriatepower source (not shown) for driving the CC masking process.

The blanket deposition subsystem 38 is shown in the lower portion ofFIG. 3B and includes several components: (1) an anode 62, (2) anelectrolyte tank 64 for holding plating solution 66, and (3) frame 74 onwhich feet 68 of subsystem 34 may sit. Subsystem 38 also includesappropriate electrical connections (not shown) for connecting the anodeto an appropriate power supply (not shown) for driving the blanketdeposition process.

The planarization subsystem 40 is shown in the lower portion of FIG. 3Cand includes a lapping plate 52 and associated motion and controlsystems (not shown) for planarizing the depositions.

In addition to teaching the use of CC masks for electrodepositionpurposes, the '630 patent also teaches that the CC masks may be placedagainst a substrate with the polarity of the voltage reversed andmaterial may thereby be selectively removed from the substrate. Itindicates that such removal processes can be used to selectively etch,engrave, and polish a substrate, e.g., a plaque.

The '630 patent further indicates that the electroplating methods andarticles disclosed therein allow fabrication of devices from thin layersof materials such as, e.g., metals, polymers, ceramics, andsemiconductor materials. It further indicates that although theelectroplating embodiments described therein have been described withrespect to the use of two metals, a variety of materials, e.g.,polymers, ceramics and semiconductor materials, and any number of metalscan be deposited either by the electroplating methods therein, or inseparate processes that occur throughout the electroplating method. Itindicates that a thin plating base can be deposited, e.g., bysputtering, over a deposit that is insufficiently conductive (e.g., aninsulating layer) so as to enable subsequent electroplating. It alsoindicates that multiple support materials (i.e. sacrificial materials)can be included in the electroplated element allowing selective removalof the support materials.

The '630 patent additionally teaches that the electroplating methodsdisclosed therein can be used to manufacture elements having complexmicrostructure and close tolerances between parts. An example is givenwith the aid of FIGS. 14A-14E of that patent. In the example, elementshaving parts that fit with close tolerances, e.g., having gaps betweenabout 1-5 um, including electroplating the parts of the device in anunassembled, preferably pre-aligned state. In such embodiments, theindividual parts can be moved into operational relation with each otheror they can simply fall together. Once together the separate parts maybe retained by clips or the like.

Another method for forming microstructures from electroplated metals(i.e. using electrochemical fabrication techniques) is taught in U.S.Pat. No. 5,190,637 to Henry Guckel, entitled “Formation ofMicrostructures by Multiple Level Deep X-ray Lithography withSacrificial Metal Layers”. This patent teaches the formation of metalstructure utilizing through mask exposures. A first layer of a primarymetal is electroplated onto an exposed plating base to fill a void in aphotoresist (the photoresist forming a through mask having a desiredpattern of openings), the photoresist is then removed and a secondarymetal is electroplated over the first layer and over the plating base.The exposed surface of the secondary metal is then machined down to aheight which exposes the first metal to produce a flat uniform surfaceextending across both the primary and secondary metals. Formation of asecond layer may then begin by applying a photoresist over the firstlayer and patterning it (i.e. to form a second through mask) and thenrepeating the process that was used to produce the first layer toproduce a second layer of desired configuration. The process is repeateduntil the entire structure is formed and the secondary metal is removedby etching. The photoresist is formed over the plating base or previouslayer by casting and patterning of the photoresist (i.e. voids formed inthe photoresist) are formed by exposure of the photoresist through apatterned mask via X-rays or UV radiation and development of the exposedor unexposed areas.

The '637 patent teaches the locating of a plating base onto a substratein preparation for electroplating materials onto the substrate. Theplating base is indicated as typically involving the use of a sputteredfilm of an adhesive metal, such as chromium or titanium, and then asputtered film of the metal that is to be plated. It is also taught thatthe plating base may be applied over an initial layer of sacrificialmaterial (i.e. a layer or coating of a single material) on the substrateso that the structure and substrate may be detached if desired. In suchcases after formation of the structure the sacrificial material formingpart of each layer of the structure may be removed along with theinitial sacrificial layer to free the structure. Substrate materialsmentioned in the '637 patent include silicon, glass, metals, and siliconwith protected semiconductor devices. A specific example of a platingbase includes about 150 angstroms of titanium and about 300 angstroms ofnickel, both of which are sputtered at a temperature of 160° C. Inanother example it is indicated that the plating base may consist of 150angstroms of titanium and 150 angstroms of nickel where both are appliedby sputtering.

Electrochemical Fabrication provides the ability to form prototypes andcommercial quantities of miniature objects, parts, structures, devices,and the like at reasonable costs and in reasonable times. In fact,Electrochemical Fabrication is an enabler for the formation of manystructures that were hitherto impossible to produce. ElectrochemicalFabrication opens the spectrum for new designs and products in manyindustrial fields. Even though Electrochemical Fabrication offers thisnew capability and it is understood that Electrochemical Fabricationtechniques can be combined with designs and structures known withinvarious fields to produce new structures, certain uses forElectrochemical Fabrication provide designs, structures, capabilitiesand/or features not known or obvious in view of the state of the art.

A need exists in various fields for miniature devices having improvedcharacteristics, reduced fabrication times, reduced fabrication costs,simplified fabrication processes, greater versatility in device design,improved selection of materials, improved material properties, more costeffective and less risky production of such devices, and/or moreindependence between geometric configuration and the selectedfabrication process.

SUMMARY OF THE INVENTION

It is an object of some embodiments of the invention to provide anenhanced electrochemical process for working with multiple structuralmaterials.

It is an object of some embodiments of the invention to provide anenhanced electrochemical process for forming structures (e.g. compliantelectrical contact elements, e.g. microprobes) that include an outercoating of a secondary structural material surrounding or at leastpartially surrounding a primary structural material.

Other objects and advantages of various embodiments of the inventionwill be apparent to those of skill in the art upon review of theteachings herein. The various embodiments of the invention, set forthexplicitly herein or otherwise ascertained from the teachings herein,may address one or more of the above objects alone or in combination, oralternatively may address some other object ascertained from theteachings herein. It is not necessarily intended that all objects beaddressed by any single aspect of the invention even though that may bethe case with regard to some aspects.

A first aspect of the invention provides a fabrication process forforming a multi-layer three-dimensional structure, comprising: (a)forming a first layer comprises at least one structural material and atleast one sacrificial material; (b) forming at least one additionallayer from at least one structural material and at least one sacrificialmaterial wherein the at least one additional layer is formed on andadhered to a previously formed layer, and wherein the first layer andthe at least one additional layer together form a multi-layerthree-dimensional structure; and (c) after formation of a plurality oflayers, separating at least a portion of the sacrificial material on aplurality of layers from the structural materials on those layers,wherein a given one of the layers comprises at least one sacrificialmaterial and at least two structural materials, wherein the at least twostructural materials comprise a core structural material located at theupper boundary of level of the given layer but not at the lower boundarylevel of the given layer and a shell structural material bounding thesides of the core material and located below the core material and abovethe lower boundary level of the given layer such at the shell structuralmaterial bounds the bottom.

A second aspect of the invention provides a fabrication process forforming a multi-layer three-dimensional structure, comprising: (a)forming a first layer comprises at least one structural material and atleast one sacrificial material; (b) forming at least one additionallayer from at least one structural material and at least one sacrificialmaterial wherein the at least one additional layer is formed on andadhered to a previously formed layer, and wherein the first layer andthe at least one additional layer together form a multi-layerthree-dimensional structure; and (c) after formation of a plurality oflayers, separating at least a portion of the sacrificial material on aplurality of layers from the structural materials on those layers,wherein a given one of the layers comprises at least one sacrificialmaterial and at least two structural materials, wherein the at least twostructural materials comprise a core structural material and a shellstructural material where the shell structural material has a base andside walls that hold the bottom and sides of the core material.

A third aspect of the invention provides a fabrication process forforming a multi-layer three-dimensional structure, comprising: (a)forming a first layer comprises at least one structural material and atleast one sacrificial material; (b) forming at least one additionallayer from at least one structural material and at least one sacrificialmaterial wherein the at least one additional layer is formed on andadhered to a previously formed layer, and wherein the first layer andthe at least one additional layer together form a multi-layerthree-dimensional structure; and (c) after formation of a plurality oflayers, separating at least a portion of the sacrificial material on aplurality of layers from the structural materials on those layers,wherein a given one of the layers comprises at least one sacrificialmaterial and at least two structural materials, wherein the at least twostructural materials comprise a core structural material located at thelower boundary level of the given layer but not at the upper-boundarylevel of the given layer and a shell structural material bounding thesides of the core material and providing a cap located above the corestructural material and below the upper boundary of the given layer suchthat the shell material bounds the top of the core structural material.

A fourth aspect of the invention provides a fabrication process forforming a multi-layer three-dimensional structure, comprising: (a)forming a first layer comprises at least one structural material and atleast one sacrificial material; (b) forming at least one additionallayer from at least one structural material and at least one sacrificialmaterial wherein the at least one additional layer is formed on andadhered to a previously formed layer, and wherein the first layer andthe at least one additional layer together form a multi-layerthree-dimensional structure; and (c) after formation of a plurality oflayers, separating at least a portion of the sacrificial material on aplurality of layers from the structural materials on those layers,wherein a given one of the layers comprises at least one sacrificialmaterial and at least two structural materials, wherein the at least twostructural materials comprise a core structural material and a shellstructural material where the shell structural material has an upper capand side walls that hold the top and sides of the core material.

A fifth aspect of the invention provides a fabrication process forforming a multi-layer three-dimensional structure, comprising: (a)forming a first layer comprises at least one structural material and atleast one sacrificial material; (b) forming at least one additionallayer from at least one structural material and at least one sacrificialmaterial wherein the at least one additional layer is formed on andadhered to a previously formed layer, and wherein the first layer andthe at least one additional layer together form a multi-layerthree-dimensional structure; and (c) after formation of a plurality oflayers, separating at least a portion of the sacrificial material on aplurality of layers from the structural materials on those layers,wherein a given one of the layers comprises at least one sacrificialmaterial and at least two structural materials, wherein the at least twostructural materials comprise a core structural material that extendsfrom a lower boundary level of the given layer to an upper boundarylevel of the given layer and a shell structural material that has sidewalls that extends from a lower boundary level of the given layer to anupper boundary level of the given layer such that the shell structuralmaterial encapsulates the sides of the core material on the given layer.

A sixth aspect of the invention provides a fabrication process forforming a multi-layer three-dimensional structure, comprising: (a)forming a first layer comprises at least one structural material and atleast one sacrificial material; (b) forming at least one additionallayer from at least one structural material and at least one sacrificialmaterial wherein the at least one additional layer is formed on andadhered to a previously formed layer, and wherein the first layer andthe at least one additional layer together form a multi-layerthree-dimensional structure; and (c) after formation of a plurality oflayers, separating at least a portion of the sacrificial material on aplurality of layers from the structural materials on those layers,wherein a given one of the layers comprises at least one sacrificialmaterial and at least two structural materials, wherein the at least twostructural materials comprise a core structural material and a shellstructural material where the shell structural material has side wallsthat encapsulate the sides of the core material on the given layer.

A seventh aspect of the invention provides a fabrication process forforming a multi-layer three-dimensional structure, comprising: (a)forming a first layer comprises at least one structural material and atleast one sacrificial material; (b) forming at least one additionallayer from at least one structural material and at least one sacrificialmaterial wherein the at least one additional layer is formed on andadhered to a previously formed layer, and wherein the first layer andthe at least one additional layer together form a multi-layerthree-dimensional structure; and (c) after formation of a plurality oflayers, separating at least a portion of the sacrificial material on aplurality of layers from the structural materials on those layers,wherein a process for forming a given layer is based at least in part ona configuration of the given layer relative to the configuration of alayer selected from the group consisting of the immediately precedinglayer and the immediately succeeding layer, and wherein the process isselected from the group consisting of (a) forming the given layer with acore structural material and a downward facing shell structuralmaterial, (b) forming the given layer with a core structural materialand an upward facing shell structural material; and (c) forming thegiven layer with a core structural material and a continuing shellstructural material.

A eighth aspect of the invention provides a fabrication process forforming a multi-layer three-dimensional structure, comprising: (a)forming a first layer comprises at least one structural material and atleast one sacrificial material; (b) forming at least one additionallayer from at least one structural material and at least one sacrificialmaterial wherein the at least one additional layer is formed on andadhered to a previously formed layer, and wherein the first layer andthe at least one additional layer together form a multi-layerthree-dimensional structure; and (c) after formation of a plurality oflayers, separating at least a portion of the sacrificial material on aplurality of layers from the structural materials on those layers,wherein a process produces a structure from a core structural materialand a shell structural material wherein the core material extendsunbroken from a given layer to a subsequent layer and is surrounded byan unbroken barrier of shell structural material and wherein thesubsequent layer is selected from the group consisting of the layerimmediately succeeding the given layer, a layer that is separated fromthe given layer by an intermediate layer, a layer is separated from thegiven layer by at least two intermediate layers, and a layer that isseparated from the given layer by more than two intermediate layers.

A ninth aspect of the invention provides a fabrication process forforming a multi-layer three-dimensional structure or an array ofstructures, comprising: (a) forming and adhering a layer of material toa previously formed layer and/or to a substrate, wherein each layercomprises at least one structural material and at least one sacrificialmaterial; (b) repeating the forming and adhering operation of (a) tobuild up a three-dimensional structure from a plurality of adheredlayers, wherein the formation of at least one given layer comprises thedeposition of at least one sacrificial material and two structuralmaterials at least one of which at least partially encapsulates theother; and (c) after formation of a plurality of layers, separating atleast a portion of the sacrificial material on a plurality of layersfrom the structural materials on those layers.

A tenth aspect of the invention provides a fabrication process forforming a multi-layer three-dimensional probe structure or array ofprobe structures, comprising: (a) forming and adhering a layer ofmaterial to a previously formed layer and/or to a substrate, wherein thelayer comprises at least one structural material and at least onesacrificial material; (b) repeating the forming and adhering operationof (a) to build up a three-dimensional structure from a plurality ofadhered layers, wherein the formation of at least a given layercomprises the deposition of at least two structural materials, at leastone of which isolates other from the sacrificial material; and (c) afterformation of a plurality of layers, separating at least a portion of thesacrificial material on a plurality of layers from the structuralmaterials on those layers, wherein the encapsulated material existswithin a lower boundary and an upper boundary of the given layer andwherein the encapsulating material for the given layer has a dimensionthat is less than a minimum feature size for the given layer.

A eleventh aspect of the invention provides a process for forming amultilayer three-dimensional structure, e.g. a probe structure or anarray of probe structures, including: (a) forming and adhering a layerof material to a previously formed layer and/or to a substrate; (b)repeating the forming and adhering operation of (a) to build up athree-dimensional structure from a plurality of adhered layers, whereinthe formation of at least a plurality of layers comprises the depositionof at least two structural materials, at least one of which isolatesother from the sacrificial material; and (c) after formation of aplurality of layers, separating at least a portion of the sacrificialmaterial on a plurality of layers from the structural materials on thoselayers.

A twelfth aspect of the invention provides a process for forming amultilayer three-dimensional structure, e.g. a probe structure or anarray of probe structures, including: (a) forming and adhering a layerof material to a previously formed layer and/or to a substrate; (b)repeating the forming and adhering operation of (a) to build up athree-dimensional structure from a plurality of adhered layers, whereinthe formation of at least a plurality of layers comprises the depositionof at least two structural materials, at least one of which is adielectric material, and the deposition of a sacrificial material; and(c) after formation of a plurality of layers, separating at least aportion of the sacrificial material on a plurality of layers from thestructural materials on those layers.

A thirteenth aspect of the invention provides a process for forming amultilayer three-dimensional structure, e.g. a probe structure or anarray of probe structures, including: (a) forming and adhering a layerof material to a previously formed layer and/or to a substrate; (b)repeating the forming and adhering operation of (a) to build up athree-dimensional structure from a plurality of adhered layers, whereinthe formation of at least a plurality of layers comprises the depositionof a sacrificial material and at least two structural materials, a firstof which encapsulates a second wherein the encapsulating first materialdoes not completely isolate regions of the second material from regionsof second material on successive layers when those regions of secondmaterial at least partially overlap; and (c) after formation of aplurality of layers, separating at least a portion of the sacrificialmaterial on a plurality of layers from the structural material on thoselayers.

Other aspects of the invention will be understood by those of skill inthe art upon review of the teachings herein. Other aspects of theinvention may involve combinations of the above noted aspects of theinvention. Other aspects of the invention may involve apparatus that canbe used in implementing one or more of the above method aspects of theinvention or may be directed to the devices or structures formed byapplication of such methods. These other aspects of the invention mayprovide various combinations of the aspects presented above as well asprovide other configurations, structures, functional relationships, andprocesses that have not been specifically set forth above but are taughtby other specific teachings set forth herein as taught by the teachingsset forth herein as a whole.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1C schematically depict side views of various stages of a CCmask plating process, while FIGS. 1D-1G schematically depict side viewsof various stages of a CC mask plating process using a different type ofCC mask.

FIGS. 2A-2F schematically depict side views of various stages of anelectrochemical fabrication process as applied to the formation of aparticular structure where a sacrificial material is selectivelydeposited while a structural material is blanket deposited.

FIGS. 3A-3C schematically depict side views of various examplesubassemblies that may be used in manually implementing theelectrochemical fabrication method depicted in FIGS. 2A-2F.

FIGS. 4A-4F schematically depict the formation of a first layer of astructure using adhered mask plating where the blanket deposition of asecond material overlays both the openings between deposition locationsof a first material and the first material itself

FIG. 4G depicts the completion of formation of the first layer resultingfrom planarizing the deposited materials to a desired level.

FIGS. 4H and 4I respectively depict the state of the process afterformation of the multiple layers of the structure and after release ofthe structure from the sacrificial material.

FIG. 5A provides a flowchart for a process according to a firstembodiment of the invention where two structural materials are used inthe formation of at least a portion of the layers of the structure,wherein a first structural material acts as a shell material and thesecond structural material acts as a core material, wherein, in general,the shell material does not fully encapsulate the core material, andwherein the sidewalls of the shell may be narrower than a minimumfeature size associated with the formation of the layer containing thewalls.

FIGS. 5B-5J schematically depict side views of various states offormation of an example device (e.g. a conductive probe for testingintegrated circuits) formed by the process of FIG. 5A where the shelland core process are used in the formation of each layer of thestructure.

FIG. 6A provides a flowchart for a process according to a secondembodiment of the invention where the structure is formed from at leasta first structural material that provides a shell material that fullyencapsulates at least a second structural material that is a corestructural material and may also be a functional structural material andwherein some layers used in forming the structure are compound layersformed of a plurality of stacked sub-layers wherein a first sub-layer ofeach compound layer provides an up-facing shell structural material anda core structural material and a second sub-layer of each compound layerprovides a capping structural material for the core structural materiallocated on the immediately preceding sub-layer, and wherein thesidewalls of the shell may be narrower than a minimum feature sizeassociated with the formation of the sub-layer containing the walls.

FIG. 6B provides a flowchart for the same process as set forth in FIG.6A with the exception that instead of viewing the up-facingencapsulating shell material and the core material as being formed on afirst sub-layer and a capping material being formed on an immediatelysucceeding second sub-layer of a compound layer, each fully planarizedlevel of structural and sacrificial material is considered a separatelayer and thus up-facing shell and core material formed on a particularlayer are followed by the formation of a corresponding capping layer.

FIGS. 6C-6N schematically depict side views of various states offormation of an example device (e.g. a conductive probe for testingintegrated circuits) formed by the process of FIG. 6A or 6B.

FIG. 7A provides a flowchart for a process according to a thirdembodiment of the invention where the structure is formed from at leasta first structural material that provides a shell material that fullyencapsulates at least a second structural material that is a corestructural material and may also be a functional structural material andwherein some layers are formed with an up-facing shell structuralmaterial and a core structural material located within a pocket formedby the shell material, wherein an immediately succeeding layer includesan initial deposition of a structural material that caps the corematerial and has a relatively thin height compared to the layerthickness, wherein continued formation of the immediately succeedinglayer occurs according to the intended configuration of that layeritself, and wherein the sidewalls of the shell may be narrower than aminimum feature size associated with the formation of the layercontaining the walls.

FIGS. 7B-7I schematically depict side views of various states of theprocess of FIG. 7A as applied to the formation of a particular examplestructure according to the third embodiment of the invention.

FIG. 8A provides a flowchart for forming a structure according to afourth embodiment of the invention, which is a combination of thefirst-third process embodiments as applied to a simplified structuralconfiguration where all or a portion of the layers are formed using acore material that may be a functional structural material that isencapsulated by a shell material and wherein the bottom and sides of theshell are formed for an nth layer as part of the nth layer while the topof the shell for the nth layer is formed by a capping material (e.g. thestructural shell material) that is effectively provided by the formationof the (n+1)^(th) layer, and wherein the sides of the shell may benarrower than a minimum feature size associated with the formation ofthe layer.

FIGS. 8B-8J illustrate various states of the process of FIG. 8A asapplied to the formation of a particular example structure (e.g. a probestructure formed from five layers while laying on its side with thecross-sectional figuration of the second layer matching or being largerthan that of the first layer, that of the third layer matching or beinglarger than that of the second layer, and with that of the fifth layermatching or being larger than the fourth layer such that the first,second, and fourth layers can be formed with a structural materialforming the sides and bottom of a shell that supports a functionalstructural material core which in turn is capped and fully encapsulatedby a structural material forming the immediately succeeding layer.

FIG. 9A provides a flowchart for forming a structure according to afifth embodiment of the invention, which unlike the first-fourthembodiments, creates a down-facing shell that encapsulates the sides andtop of a core material and may be used to create structures withenhanced properties depending on geometric configuration of the currentlayer with respect to a preceding layer, the type of shell and corematerial being used, the type of coring and shelling, if any, used onthe preceding layer, and the like, and wherein the shell side walls maybe narrower than a minimum feature size associated with the formation ofa layer.

FIGS. 9B-9K illustrate various states of the process of FIG. 9A asapplied to the formation of a particular sample layer of a structurewhich has a lateral size similar to that of a previous layer on which itis formed with the exception that the previous layer was formed using anup-facing shell and core method (such as that used in one of thefirst-fourth embodiments) and such that a core is formed starting in andextending from an immediately preceding layer and extending into andending in the current layer.

FIG. 10A provides a flowchart for forming a structure according to asixth embodiment of the invention wherein a structure is formed with atleast one layer that includes a shell and core where the core extendsfrom the bottom of the nth layer to the top of the nth layer with shellwalls surrounding the sides of the core and wherein the shell walls maybe narrower than a minimum feature size associated with the formation ofthe layer.

FIGS. 10B-10J illustrate various states of the process of FIG. 10A asapplied to the formation of a particular sample layer of a structurewhich has a lateral size similar to that of a previous layer on which itis formed with the exception that the previous layer was formed using anup-facing shell and core method (such as that used in one of thefirst-fourth embodiments) and such that a core is formed starting in andextending from an immediately preceding layer and extending into andthrough the current layer.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

Electrochemical Fabrication in General:

FIGS. 1A-1G, 2A-2F, and 3A-3C illustrate various features of one form ofelectrochemical fabrication. Other electrochemical fabricationtechniques are set forth in the '630 patent referenced above, in thevarious previously incorporated publications, in various other patentsand patent applications incorporated herein by reference. Still othersmay be derived from combinations of various approaches described inthese publications, patents, and applications, or are otherwise known orascertainable by those of skill in the art from the teachings set forthherein. All of these techniques may be combined with those of thevarious embodiments of various aspects of the invention to yieldenhanced embodiments. Still other embodiments may be derived fromcombinations of the various embodiments explicitly set forth herein.

FIGS. 4A-4I illustrate side views of various states in an alternativemulti-layer, multi-material electrochemical fabrication process. FIGS.4A-4G illustrate various stages in the formation of a single layer of amulti-layer fabrication process where a second metal is deposited on afirst metal as well as in openings in the first metal so that the firstand second metal form part of the layer. In FIG. 4A a side view of asubstrate 82 having a surface 88 is shown, onto which patternablephotoresist 84 is cast as shown in FIG. 4B. In FIG. 4C, a pattern ofresist is shown that results from the curing, exposing, and developingof the resist. The patterning of the photoresist 84 results in openingsor apertures 92(a)-92(c) extending from a surface 86 of the photoresistthrough the thickness of the photoresist to surface 88 of the substrate82. In FIG. 4D a metal 94 (e.g. nickel) is shown as having beenelectroplated into the openings 92(a)-92(c). In FIG. 4E the photoresisthas been removed (i.e. chemically stripped) from the substrate to exposeregions of the substrate 82 which are not covered with the first metal94. In FIG. 4F a second metal 96 (e.g. silver) is shown as having beenblanket electroplated over the entire exposed portions of the substrate82 (which is conductive) and over the first metal 94 (which is alsoconductive). FIG. 4G depicts the completed first layer of the structurewhich has resulted from the planarization of the first and second metalsdown to a height that exposes the first metal and sets a thickness forthe first layer. In FIG. 4H the result of repeating the process stepsshown in FIGS. 4B-4G several times to form a multi-layer structure isshown where each layer consists of two materials. For most applications,one of these materials is removed as shown in FIG. 4I to yield a desired3-D structure 98 (e.g. component or device).

Various embodiments of various aspects of the invention are directed toformation of three-dimensional structures from materials some, or all,of which may be electrodeposited (as illustrated in FIGS. 1A-4I) orelectroless deposited. Some of these structures may be formed form asingle build level formed from one or more deposited materials whileothers are formed from a plurality of build layers each including atleast two materials (e.g. two or more layers, more preferably five ormore layers, and most preferably ten or more layers). In someembodiments, layer thicknesses may be as small as one micron or as largeas fifty microns. In other embodiments, thinner layers may be used whilein other embodiments, thicker layers may be used. In some embodimentsstructures having features positioned with micron level precision andminimum features size on the order of tens of microns are to be formed.In other embodiments structures with less precise feature placementand/or larger minimum features may be formed. In still otherembodiments, higher precision and smaller minimum feature sizes may bedesirable. In the present application meso-scale and millimeter scalehave the same meaning and refer to devices that may have one or moredimensions extending into the 0.5-20 millimeter range, or somewhatlarger and with features positioned with precision in the 10-100 micronrange and with minimum features sizes on the order of 100 microns.

The various embodiments, alternatives, and techniques disclosed hereinmay form multi-layer structures using a single patterning technique onall layers or using different patterning techniques on different layers.For example, various embodiments of the invention may perform selectivepatterning operations using conformable contact masks and maskingoperations (i.e. operations that use masks which are contacted to butnot adhered to a substrate), proximity masks and masking operations(i.e. operations that use masks that at least partially selectivelyshield a substrate by their proximity to the substrate even if contactis not made), non-conformable masks and masking operations (i.e. masksand operations based on masks whose contact surfaces are notsignificantly conformable), and/or adhered masks and masking operations(masks and operations that use masks that are adhered to a substrateonto which selective deposition or etching is to occur as opposed toonly being contacted to it). Conformable contact masks, proximity masks,and non-conformable contact masks share the property that they arepreformed and brought to, or in proximity to, a surface which is to betreated (i.e. the exposed portions of the surface are to be treated).These masks can generally be removed without damaging the mask or thesurface that received treatment to which they were contacted, or locatedin proximity to. Adhered masks are generally formed on the surface to betreated (i.e. the portion of that surface that is to be masked) andbonded to that surface such that they cannot be separated from thatsurface without being completely destroyed or damaged beyond any pointof reuse. Adhered masks may be formed in a number of ways including (1)by application of a photoresist, selective exposure of the photoresist,and then development of the photoresist, (2) selective transfer ofpre-patterned masking material, and/or (3) direct formation of masksfrom computer controlled depositions of material.

Patterning operations may be used in selectively depositing materialand/or may be used in the selective etching of material. Selectivelyetched regions may be selectively filled in or filled in via blanketdeposition, or the like, with a different desired material. In someembodiments, the layer-by-layer build up may involve the simultaneousformation of portions of multiple layers. In some embodiments,depositions made in association with some layer levels may result indepositions to regions associated with other layer levels (i.e. regionsthat lie within the top and bottom boundary levels that define adifferent layer's geometric configuration). Such use of selectiveetching and interlaced material deposition in association with multiplelayers is described in U.S. patent application Ser. No. 10/434,519, bySmalley, now U.S. Pat. No. 7,252,861, and entitled “Methods of andApparatus for Electrochemically Fabricating Structures Via InterlacedLayers or Via Selective Etching and Filling of Voids” which is herebyincorporated herein by reference as if set forth in full.

Temporary substrates on which structures may be formed may be of thesacrificial-type (i.e. destroyed or damaged during separation ofdeposited materials to the extent they cannot be reused),non-sacrificial-type (i.e. not destroyed or excessively damaged, i.e.not damaged to the extent they may not be reused, e.g. with asacrificial or release layer located between the substrate and theinitial layers of a structure that is formed). Non-sacrificialsubstrates may be considered reusable, with little or no rework (e.g.replanarizing one or more selected surfaces or applying a release layer,and the like) though they may or may not be reused for a variety ofreasons.

Definitions

This section of the specification is intended to set forth definitionsfor a number of specific terms that may be useful in describing thesubject matter of the various embodiments of the invention. It isbelieved that the meanings of most if not all of these terms is clearfrom their general use in the specification but they are set forthhereinafter to remove any ambiguity that may exist. It is intended thatthese definitions be used in understanding the scope and limits of anyclaims that use these specific terms. As far as interpretation of theclaims of this patent disclosure are concerned, it is intended thatthese definitions take presence over any contradictory definitions orallusions found in any materials which are incorporated herein byreference.

“Build” as used herein refers, as a verb, to the process of building adesired structure (or part) or plurality of structures (or parts) from aplurality of applied or deposited materials which are stacked andadhered upon application or deposition or, as a noun, to the physicalstructure (or part) or structures (or parts) formed from such a process.Depending on the context in which the term is used, such physicalstructures may include a desired structure embedded within a sacrificialmaterial or may include only desired physical structures which may beseparated from one another or may require dicing and/or slicing to causeseparation.

“Build axis” or “build orientation” is the axis or orientation that issubstantially perpendicular to substantially planar levels of depositedor applied materials that are used in building up a structure. Theplanar levels of deposited or applied materials may be or may not becompletely planar but are substantially so in that the overall extent oftheir cross-sectional dimensions are significantly greater than theheight of any individual deposit or application of material (e.g. 100,500, 1000, 5000, or more times greater). The planar nature of thedeposited or applied materials may come about from use of a process thatleads to planar deposits or it may result from a planarization process(e.g. a process that includes mechanical abrasion, e.g. lapping, flycutting, grinding, or the like) that is used to remove material regionsof excess height. Unless explicitly noted otherwise, “vertical” as usedherein refers to the build axis or nominal build axis (e.g. if thelayers are not stacking with perfect registration) while “horizontal”refers to a direction within the plane of the layers (i.e. the planethat is substantially perpendicular to the build axis). For convenienceof terminology and without implying a particular physical buildorientation, successive layers shall be considered to be added abovepreviously formed layers and preceding layers will be considered toexist below later formed layers. For example during electroplatingactual build orientation may be vertical up-facing or horizontal whilefor planarization actual build orientation may be horizontal ordown-facing vertical but successive layers will still be considered tobe formed on or above previously formed layers unless explicitlyindicated otherwise.

“Build layer” or “layer of structure” as used herein does not refer to adeposit of a specific material but instead refers to a region of a buildlocated between a lower boundary level and an upper boundary level whichgenerally defines a single cross-section of a structure being formed orstructures which are being formed in parallel. Depending on the detailsof the actual process used to form the structure, build layers aregenerally formed on and adhered to previously formed build layers. Insome processes the boundaries between build layers are defined byplanarization operations which result in successive build layers beingformed on substantially planar upper surfaces of previously formed buildlayers. In some embodiments, the substantially planar upper surface ofthe preceding build layer may be textured to improve adhesion betweenthe layers. In other build processes, openings may exist in or be formedin the upper surface of a previous but only partially formed build layeror build layers such that the openings in the previous build layer orbuild layers are filled with materials deposited in association withcurrent build layer which will cause interlacing of build layers andmaterial deposits. Such interlacing is described in U.S. patentapplication Ser. No. 10/434,519 now U.S. Pat. No. 7,252,861. Thisreferenced application is incorporated herein by reference as if setforth in full. In most embodiments, a build layer includes at least oneprimary structural material and at least one primary sacrificialmaterial. However, in some embodiments, two or more primary structuralmaterials may be used without a primary sacrificial material (e.g. whenone primary structural material is a dielectric and the other is aconductive material). In some embodiments, build layers aredistinguishable from each other by the source of the data that is usedto yield patterns of the deposits, applications, and/or etchings ofmaterial that form the respective build layers. For example, datadescriptive of a structure to be formed which is derived from dataextracted from different vertical levels of a data representation of thestructure define different build layers of the structure. The verticalseparation of successive pairs of such descriptive data may define thethickness of build layers associated with the data. As used herein, attimes, “build layer” may be loosely referred simply as “layer”. In manyembodiments, deposition thickness of primary structural or sacrificialmaterials (i.e. the thickness of any particular material after it isdeposited) is generally greater than the layer thickness and a netdeposit thickness is set via one or more planarization processes whichmay include, for example, mechanical abrasion (e.g. lapping, flycutting, polishing, and the like) and/or chemical etching (e.g. usingselective or non-selective etchants). The lower boundary and upperboundary for a build layer may be set and defined in different ways.From a design point of view they may be set based on a desired verticalresolution of the structure (which may vary with height). From a datamanipulation point of view, the vertical layer boundaries may be definedas the vertical levels at which data descriptive of the structure isprocessed or the layer thickness may be defined as the height separatingsuccessive levels of cross-sectional data that dictate how the structurewill be formed. From a fabrication point of view, depending on the exactfabrication process used, the upper and lower layer boundaries may bedefined in a variety of different ways. For example by planarizationlevels or effective planarization levels (e.g. lapping levels, flycutting levels, chemical mechanical polishing levels, mechanicalpolishing levels, vertical positions of structural and/or sacrificialmaterials after relatively uniform etch back following a mechanical orchemical mechanical planarization process). For example, by levels atwhich process steps or operations are repeated. At levels at which, atleast theoretically, lateral extents of structural material can bechanged to define new cross-sectional features of a structure.

“Layer thickness” is the height along the build axis between a lowerboundary of a build layer and an upper boundary of that build layer.

“Planarization” is a process that tends to remove materials, above adesired plane, in a substantially non-selective manner such that alldeposited materials are brought to a substantially common height ordesired level (e.g. within 20%, 10%, 5%, or even 1% of a desired layerboundary level). For example, lapping removes material in asubstantially non-selective manner though some amount of recession ofone material versus another material may occur (e.g. copper may recessrelative to nickel). Planarization may occur primarily via mechanicalmeans, e.g. lapping, grinding, fly cutting, milling, sanding, abrasivepolishing, frictionally induced melting, other machining operations, orthe like (i.e. mechanical planarization). Mechanical planarization maybe followed or preceded by thermally induced planarization (e.g.melting) or chemically induced planarization (e.g. etching).Planarization may occur primarily via a chemical and/or electrical means(e.g. chemical etching, electrochemical etching, or the like).Planarization may occur via a simultaneous combination of mechanical andchemical etching (e.g. chemical mechanical polishing (CMP)).

“Structural material” as used herein refers to a material that remainspart of the structure when put into use.

“Supplemental structural material” as used herein refers to a materialthat forms part of the structure when the structure is put to use but isnot added as part of the build layers but instead is added to aplurality of layers simultaneously (e.g. via one or more coatingoperations that applies the material, selectively or in a blanketfashion, to a one or more surfaces of a desired build structure that hasbeen released from a sacrificial material.

“Primary structural material” as used herein is a structural materialthat forms part of a given build layer and which is typically depositedor applied during the formation of that build layer and which makes upmore than 20% of the structural material volume of the given buildlayer. In some embodiments, the primary structural material may be thesame on each of a plurality of build layers or it may be different ondifferent build layers. In some embodiments, a given primary structuralmaterial may be formed from two or more materials by the alloying ordiffusion of the two or more materials to form a single material.

“Secondary structural material” as used herein is a structural materialthat forms part of a given build layer and is typically deposited orapplied during the formation of the given build layer but is not aprimary structural material as it individually accounts for only a smallvolume of the structural material associated with the given layer. Asecondary structural material will account for less than 20% of thevolume of the structural material associated with the given layer. Insome preferred embodiments, each secondary structural material mayaccount for less than 10%, 5%, or even 2% of the volume of thestructural material associated with the given layer. Examples ofsecondary structural materials may include seed layer materials,adhesion layer materials, barrier layer materials (e.g. diffusionbarrier material), and the like. These secondary structural materialsare typically applied to form coatings having thicknesses less than 2microns, 1 micron, 0.5 microns, or even 0.2 microns. The coatings may beapplied in a conformal or directional manner (e.g. via CVD, PVD,electroless deposition, or the like). Such coatings may be applied in ablanket manner or in a selective manner. Such coatings may be applied ina planar manner (e.g. over previously planarized layers of material) astaught in U.S. patent application Ser. No. 10/607,931, now U.S. Pat. No.7,239,219. In other embodiments, such coatings may be applied in anon-planar manner, for example, in openings in and over a patternedmasking material that has been applied to previously planarized layersof material as taught in U.S. patent application Ser. No. 10/841,383,now U.S. Pat. No. 7,195,989. These referenced applications areincorporated herein by reference as if set forth in full herein.

“Functional structural material” as used herein is a structural materialthat would have been removed as a sacrificial material but for itsactual or effective encapsulation by other structural materials.Effective encapsulation refers, for example, to the inability of anetchant to attack the functional structural material due toinaccessibility that results from a very small area of exposure and/ordue to an elongated or tortuous exposure path. For example, large(10,000 μm²) but thin (e.g. less than 0.5 microns) regions ofsacrificial copper sandwiched between deposits of nickel may defineregions of functional structural material depending on ability of arelease etchant to remove the sandwiched copper.

“Stand alone structural material” or “genuine structural material” is astructural material that is resistive or not substantially removed by asacrificial material etchant that is used in separating sacrificial andstructural materials.

“Sacrificial material” is material that forms part of a build layer butis not a structural material. Sacrificial material on a given buildlayer is separated from structural material on that build layer afterformation of that build layer is completed and more generally is removedfrom a plurality of layers after completion of the formation of theplurality of layers during a “release” process that removes the bulk ofthe sacrificial material or materials. In general sacrificial materialis located on a build layer during the formation of one, two, or moresubsequent build layers and is thereafter removed in a manner that doesnot lead to a planarized surface. Materials that are applied primarilyfor masking purposes, i.e. to allow subsequent selective deposition oretching of a material, e.g. photoresist that is used in forming a buildlayer but does not form part of the build layer, or that exist as partof a build for less than one or two complete build layer formationcycles are not considered sacrificial materials as the term is usedherein but instead shall be referred as masking materials or astemporary materials. Sacrificial material removal or separationprocesses are sometimes referred to as a release process and may or maynot involve the separation of structural material from a buildsubstrate. In many embodiments, sacrificial material within a givenbuild layer is not removed until all build layers making up thethree-dimensional structure have been formed. Of course sacrificialmaterial may be, and typically is, removed from above the upper level ofa current build layer during planarization operations during theformation of the current build layer. Sacrificial material is typicallyremoved via a chemical etching operation but in some embodiments may beremoved via a melting operation or electrochemical etching operation. Intypical structures, the removal of the sacrificial material (i.e.release of the structural material from the sacrificial material) doesnot result in planarized surfaces but instead results in surfaces thatare dictated by the boundaries of structural materials located on eachbuild layer. Sacrificial materials are typically distinct fromstructural materials by having different properties therefrom (e.g.chemical etchability, hardness, melting point, etc.) but in some cases,as noted previously, what would have been a sacrificial material maybecome a structural material by its actual or effective encapsulation byother structural materials. Similarly, structural materials may be usedto form sacrificial structures that are separated from a desiredstructure during a release process via the sacrificial structures beingonly attached to sacrificial material or potentially by dissolution ofthe sacrificial structures themselves using a process that isinsufficient to reach structural material that is intended to form partof a desired structure. It should be understood that in someembodiments, small amounts of structural material may be removed, afteror during release of sacrificial material. Such small amounts ofstructural material may have been inadvertently formed due toimperfections in the fabrication process or may result from the properapplication of the process but may result in features that are less thanoptimal (e.g. layers with stairs steps in regions where smooth slopedsurfaces are desired. In such cases the volume of structural materialremoved is typically minuscule compared to the amount that is retainedand thus such removal is ignored when labeling materials as sacrificialor structural. Sacrificial materials are typically removed by adissolution process, or the like, that destroys the geometricconfiguration of the sacrificial material as it existed on the buildlayers. In many embodiments, the sacrificial material is a conductivematerial such as a metal. As will be discussed hereafter, maskingmaterials though typically sacrificial in nature are not termedsacrificial materials herein unless they meet the required definition ofsacrificial material.

“Supplemental sacrificial material” as used herein refers to a materialthat does not form part of the structure when the structure is put touse and is not added as part of the build layers but instead is added toa plurality of layers simultaneously (e.g. via one or more coatingoperations that applies the material, selectively or in a blanketfashion, to a one or more surfaces of a desired build structure that hasbeen released from an initial sacrificial material. This supplementalsacrificial material will remain in place for a period of time and/orduring the performance of certain post layer formation operations, e.g.to protect the structure that was released from a primary sacrificialmaterial, but will be removed prior to putting the structure to use.

“Primary sacrificial material” as used herein is a sacrificial materialthat is located on a given build layer and which is typically depositedor applied during the formation of that build layer and which makes upmore than 20% of the sacrificial material volume of the given buildlayer. In some embodiments, the primary sacrificial material may be thesame on each of a plurality of build layers or may be different ondifferent build layers. In some embodiments, a given primary sacrificialmaterial may be formed from two or more materials by the alloying ordiffusion of the two or more materials to form a single material.

“Secondary sacrificial material” as used herein is a sacrificialmaterial that is located on a given build layer and is typicallydeposited or applied during the formation of the build layer but is nota primary sacrificial material as it individually accounts for only asmall volume of the sacrificial material associated with the givenlayer. A secondary sacrificial material will account for less than 20%of the volume of the sacrificial material associated with the givenlayer. In some preferred embodiments, each secondary sacrificialmaterial may account for less than 10%, 5%, or even 2% of the volume ofthe sacrificial material associated with the given layer. Examples ofsecondary structural materials may include seed layer materials,adhesion layer materials, barrier layer materials (e.g. diffusionbarrier material), and the like. These secondary sacrificial materialsare typically applied to form coatings having thicknesses less than 2microns, 1 micron, 0.5 microns, or even 0.2 microns). The coatings maybe applied in a conformal or directional manner (e.g. via CVD, PVD,electroless deposition, or the like). Such coatings may be applied in ablanket manner or in a selective manner. Such coatings may be applied ina planar manner (e.g. over previously planarized layers of material) astaught in U.S. patent application Ser. No. 10/607,931, now U.S. Pat. No.7,239,219. In other embodiments, such coatings may be applied in anon-planar manner, for example, in openings in and over a patternedmasking material that has been applied to previously planarized layersof material as taught in U.S. patent application Ser. No. 10/841,383,now U.S. Pat. No. 7,195,989. These referenced applications areincorporated herein by reference as if set forth in full herein.

“Adhesion layer”, “seed layer”, “barrier layer”, and the like refer tocoatings of material that are thin in comparison to the layer thicknessand thus generally form secondary structural material portions orsacrificial material portions of some layers. Such coatings may beapplied uniformly over a previously formed build layer, they may beapplied over a portion of a previously formed build layer and overpatterned structural or sacrificial material existing on a current (i.e.partially formed) build layer so that a non-planar seed layer results,or they may be selectively applied to only certain locations on apreviously formed build layer. In the event such coatings arenon-selectively applied, selected portions may be removed (1) prior todepositing either a sacrificial material or structural material as partof a current layer or (2) prior to beginning formation of the next layeror they may remain in place through the layer build up process and thenetched away after formation of a plurality of build layers.

“Masking material” is a material that may be used as a tool in theprocess of forming a build layer but does not form part of that buildlayer. Masking material is typically a photopolymer or photoresistmaterial or other material that may be readily patterned. Maskingmaterial is typically a dielectric. Masking material, though typicallysacrificial in nature, is not a sacrificial material as the term is usedherein. Masking material is typically applied to a surface during theformation of a build layer for the purpose of allowing selectivedeposition, etching, or other treatment and is removed either during theprocess of forming that build layer or immediately after the formationof that build layer.

“Multilayer structures” are structures formed from multiple build layersof deposited or applied materials.

“Multilayer three-dimensional (or 3D or 3-D) structures” are multilayerstructures that are formed from at least two layers where the structuralmaterial portion of at least two of the at least two layers at leastpartially overlap and are bonded together but where at least one of thelayers has a portion that does not completely overlap structuralmaterial portions of the other. In other words a Boolean intersection ofthe area covered by the two layers is non-zero and a Boolean subtractionof the area covered by at least one of the layers relative to the otherlayer is non-zero (i.e. an upper layer has a down-facing portionrelative to the lower layer or the lower layer has an up-facing portionrelative to the upper layer.

“Complex multilayer three-dimensional (or 3D or 3-D) structures” aremultilayer three-dimensional structures formed from at least threelayers where, when considering a single structure, a line may be definedthat hypothetically extends vertically through at least some portion ofthe build layers of the structure and extends from structural materialthrough sacrificial material and back through structural material orwill extend from sacrificial material through structural material andback through sacrificial material (these might be termed verticallycomplex multilayer three-dimensional structures). Alternatively, complexmultilayer three-dimensional structures may be defined as multilayerthree-dimensional structures formed from at least two layers where, whenconsidering a single structure, a line may be defined thathypothetically extends horizontally through at least some portion of abuild layer of the structure that will extend from structural materialthrough sacrificial material and back through structural material orwill extend from sacrificial material through structural material andback through sacrificial material (these might be termed horizontallycomplex multilayer three-dimensional structures). Worded another way, incomplex multilayer three-dimensional structures, a vertically orhorizontally extending hypothetical line will extend from one orstructural material or void (when the sacrificial material is removed)to the other of void or structural material and then back to structuralmaterial or void as the line is traversed along at least a portion ofthe line.

“Moderately complex multilayer three-dimensional (or 3D or 3-D)structures are complex multilayer 3D structures for which, whenconsidering a single structure, the alternating of void and structure orstructure and void not only exists along one of a vertically orhorizontally extending line but along lines extending both verticallyand horizontally.

“Highly complex multilayer (or 3D or 3-D) structures are complexmultilayer 3D structures for which, when considering a single structure,the structure-to-void-to-structure or void-to-structure-to-voidalternating occurs not once but occurs a plurality of times along adefinable horizontally or vertically extending line.

“Up-facing feature” is an element dictated by the cross-sectional datafor a given build layer “n” and a next build layer “n+1” that is to beformed from a given material that exists on the build layer “n” but doesnot exist on the immediately succeeding build layer “n+1”. Forconvenience the term “up-facing feature” will apply to such featuresregardless of the build orientation.

“Down-facing feature” is an element dictated by the cross-sectional datafor a given build layer “n” and a preceding build layer “n−1” that is tobe formed from a given material that exists on build layer “n” but doesnot exist on the immediately preceding build layer “n−1”. As withup-facing features, the term “down-facing feature” shall apply to suchfeatures regardless of the actual build orientation.

“Continuing region” is the portion of a given build layer “n” that isdictated by the cross-sectional data for the given build layer “n”, anext build layer “n+1” and a preceding build layer “n−1” that is neitherup-facing nor down-facing for the build layer “n”.

“Minimum feature size” refers to a necessary or desirable spacingbetween structural material elements on a given layer that are to remaindistinct in the final device configuration. If the minimum feature sizeis not maintained on a given layer, the fabrication process may resultin structural material inadvertently bridging the two structuralelements due to masking material failure or failure to appropriatelyfill voids with sacrificial material during formation of the given layersuch that during formation of a subsequent layer structural materialinadvertently fills the void. More care during fabrication can lead to areduction in minimum feature size or a willingness to accept greaterlosses in productivity can result in a decrease in the minimum featuresize. However, during fabrication for a given set of process parameters,inspection diligence, and yield (successful level of production) aminimum design feature size is set in one way or another. The abovedescribed minimum feature size may more appropriately be termed minimumfeature size of sacrificial material regions. Conversely a minimumfeature size for structure material regions (minimum width or length ofstructural material elements) may be specified. Depending on thefabrication method and order of deposition of structural material andsacrificial material, the two types of minimum feature sizes may bedifferent. In practice, for example, using electrochemical fabricationmethods and described herein, the minimum features size on a given layermay be roughly set to a value that approximates the layer thickness usedto form the layer and it may be considered the same for both structuraland sacrificial material widths and lengths. In some more rigorouslyimplemented processes, examination regiments, and rework requirements,it may be set to an amount that is 80%, 50%, or even 30% of the layerthickness. Other values or methods of setting minimum feature sizes maybe set.

“Sub-layer” as used herein refers to a portion of a build layer thattypically includes the full lateral extents of that build layer but onlya portion of its height. A sub-layer is usually a vertical portion ofbuild layer that undergoes independent processing compared to anothersub-layer of that build layer. In fact as used herein, use of asub-layer in the formation of a layer requires use of at least a secondsub-layer in formation of that layer and as such, the sub-layers shallbe numbered (e.g. first, second, etc., depending on their order offormation) and the layer of which they form a part will be referred to aas a “compound layer” to avoid confusion with normal layer build upprocesses as set forth herein.

Fabrication Methods for Providing Enhanced Structural Properties

The teachings of the present application are centered around sixembodiments, or layer processing methods, and numerous variationsthereof which are set forth explicitly herein.

The first-sixth embodiments provide methods for forming devices thatinclude regions of partially or completely encapsulated material wherebythe one or more encapsulated materials function as structural materialshaving different chemical, mechanical, electrical, and/or thermalproperties relative to the encapsulating material. Desired mechanical,chemical, electrical, and/or thermal properties for the device as awhole, or for a particular portion of the device, may be achieved byselecting appropriate combinations and quantities of encapsulating andencapsulated materials. For example, one or more of the materials mayprovide high yield strength or high temperature stability (e.g. theencapsulating material or materials) while one or more other materials(e.g. the encapsulated material or materials) provide higher thermaland/or electrical conductivity where the overall properties are derivedfrom the properties of the two or more structural materials that areutilized, their relative amounts, and their relative positions (e.g.locations and orientations) within the device.

The first embodiment provides a method for forming a multi-layerstructure using a shell structural material, a core structural materialand at least one sacrificial material with only a single selectivepatterning needing to occur per layer and wherein under generalcircumstances only partial encapsulation of the core structural materialoccurs by the shell structural material but under specific circumstancescomplete encapsulation can occur. In some variations of this embodiment,the method may allow multiple structural materials to be formed duringthe creation of individual layers where such modification may beutilized in forming only a portion of the layers (i.e. on one or more ofthe layers but not all the layers). In this embodiment, the shellstructural material forms upward facing pockets (i.e. facing away frompreviously formed layers) for holding the core structural material. Insome variations of this embodiment, multiple masking operations may beused during the formation of individual layers to yield structures witheven further enhanced configurations or properties.

FIG. 5A provides a flowchart for a process according to the firstembodiment of the invention where two structural materials are used inthe formation of at least a portion of the layers of the structure,wherein a first structural material acts as a shell material and thesecond structural material acts as a core material, wherein, in general,the shell material does not fully encapsulate the core material, andwherein the sidewalls of the shell may be narrower than a minimumfeature size associated with the formation of the layer containing thewalls.

The process of FIG. 5A starts with step 151 which call for providing abuild substrate on which a structure can be formed.

Next the process moves to step 152 which calls for the providing of anoptional release layer on the substrate which may, for example, be usedto allow removal of the structure from the substrate after formation ofthe multiple layers of the structure.

Next the process, in step 153, sets a layer count variable equal to one(n=1) in preparation for beginning formation of a first layer of thestructure. The process then moves forward to a processing branch ordecision block, step 154, where an enquiry is made as to whether or notthe particular layer that will be formed is to be formed with anup-facing shell configuration and a corresponding core material. If theanswer is “yes” the process moves forward to step 158 but if the answeris “no”, the process moves forward to step 155 which calls for theformation of the current layer “n” in any desired manner. If step 155 isimplemented the formation of layer “n” may be performed, for example,using one of the layer formation methods set forth in the backgroundsection of the current application, one of the layer formation methodsset forth in one of the patents or applications that are incorporated inthe current application by reference, or one of the alternative methodsset forth in this detailed description of this application. A specificexample of a formation process includes (1) selectively depositing afirst material (e.g. one of a structural material and a sacrificialmaterial) to form part of the current layer “n”; (2) depositing at leastone additional material to form another part of the current layer “n”(e.g. the other of a structural material and a sacrificial material);and (3) planarizing the deposited materials to set a boundary level forcurrent layer.

Turning back to step 158, a sacrificial material is deposited by apatterned deposition (e.g. electrodeposition into one or more voids in amasking material). After removal of any masking material that was usedin the deposition step, a void is left behind into which a structuralmaterial can be deposited in accordance with step 160. The depositedsacrificial material forms a portion of the current layer. In someembodiment variations, the sacrificial material may be deposited bydirect deposition, e.g. ink jetting or controlled extrusion, while inother embodiment variations, the sacrificial material may be blanketdeposited and then patterned by selective etching.

Next the process moves forward to Step 160 which calls for thedeposition of a structural material to a depth or thickness that is lessthan the desired layer thickness. This deposition will result in a shellof genuine structural material forming a base or floor and side wallsalong the edges of the sacrificial material. The depth of deposition isselected to provide a desired base thickness a desired wall thickness,and a desired void thickness (i.e. a thickness between the top of theshell material and the overlying boundary level of the layer) which willhold a core material that will be deposited in step 161. The shellmaterial may be deposited in a blanket manner so that it not only fillsthe void but also overlies the upper surface of the sacrificial materialor alternatively it may be deposited selectively (e.g. in one of themanners noted above in association with step 158).

Next the process moves forward to Step 161 which calls for thedeposition of a core material. Unless the next layer to be formedprovides for completing the encapsulation of the core material depositedin this step, the core material needs to be a genuine structuralmaterial like the shell material, otherwise it may be subject to removalwhen the sacrificial material is removed in a subsequent step.

The process next moves to step 162 which calls for the planarization ofthe deposited sacrificial and structural materials to set a boundarylevel of the current layer. The planarization step may involve a varietyof different operations or steps that are based on the variousplanarization processes mentioned elsewhere herein. In some embodimentvariations of this step may be implemented using one or more of themethods set forth in U.S. Pat. No. 7,271,888, by Frodis et al., andentitled “Method and Apparatus for Maintaining Parallelism of Layersand/or Achieving Desired Thicknesses of Layers During theElectrochemical Fabrication of Structures” which is hereby incorporatedherein by reference.

From step 162 and step 155, the process moves forward to step 180 whichenquires as to whether or not layer “n” just formed is the last layer,i.e. does n=N?, wherein N is the number of the last layer. If the answeris “no” the process proceeds to step 185 where the current layer numberis incremented by 1, i.e. n=n+1. After step 185 the process loops backto step 154 which was discussed above. If the answer is “yes” from step180, layer fabrication is complete and the process moves forward to thepost layer formation steps 181-184.

Step 181 calls for the, optional performance of any pre-release, postlayer formation step. Such a step might, for example, include attachinga permanent substrate, performing diffusion bonding, dicing one or morestructures from other structures, performance of testing operations ontest structures that may have been formed along with structures and/orapplication of a barrier material (e.g. photoresist or tape) to provideeasy release locations and hard to release (i.e. shielded) locations.

Next the process moves forward to step 182 which calls for the releaseof the structure or structures (or at least a portion of thestructures). This release may occur by a variety of methods. Suchmethods may include, for example, those steps forth explicitly herein orthose incorporated herein by reference (such as those set forth in the'347 application referenced in the table below).

Next the process moves forward to step 183 which calls for the optionalperformance of any post release formation steps. These steps for examplemay include coating, testing, and/or assembly steps such as attachmentof a released structure to a desired substrate or other component.

Finally the process ends with step 184 which calls for putting thestructure to any desired use.

FIGS. 5B-5J schematically depict side views of various states offormation of an example device (e.g. a conductive probe for testingintegrated circuits) formed by the process of FIG. 5A where the shelland core process are used in the formation of each layer of thestructure. In this illustration of the process of the first embodiment,the device is formed with its longitudinal or vertical axis parallel tothat of the build axis. In other examples the device being formed mayhave a longitudinal or vertical axis that lies in the plane of thelayers in others it may be directed in a non-vertical or non-horizontaldirection.

In FIG. 5B, a temporary substrate 102 is provided according to step 151of FIG. 5A.

In FIG. 5C the state of the process is shown after a release layer ofsacrificial material 104, e.g. Cu, is supplied (e.g. applied) accordingto step 152 of FIG. 5A. This application may occur in a variety of ways,such as, for example, via application and bonding of a sheet material orvia deposition followed by planarization wherein the deposition processmay include one or more of electroplating, electroless deposition,sputtering or other PVD process, or CVD.

In FIG. 5D, a second level of the sacrificial material 104 has beenselectively plated to form a portion of a first layer according to step158 of FIG. 5A.

In FIG. 5E, a structural material or coating 106 (e.g., Au, Ag, Ni,Ni—Co, Ni—Mn, Ni—P, Pd, Pd—Co, or the like) is shown after blanketdepositing has occurred according to step 160 of FIG. 5A. The thicknessof this coating may be thin compared to the layer thickness or may berelative thick but does not reach or exceed the layer thickness. Forexample, layer thicknesses may range from 1-50 microns, or more, whilecoating thicknesses may range from less than 10% to something more than90% of the layer thickness. In many implementations the coatingthicknesses will typically be less than 25-50% of the layer thicknesses.In some embodiments these thicknesses may range from 1-20 microns andmay more specifically be in the range of 5-20 microns or even 10-15microns depending on the thickness of the shell desired. In somevariations of the present embodiment the deposition of a firststructural material or coating material 106 may occur in a selectivemanner by use of a mask that leaves openings over the void regions 108in the sacrificial material. The thickness of the deposited coatingmaterial 106 is less than an intended thickness of the layer (i.e. itsupper surface is located below the upper boundary level for the currentlayer so that it provides a cup or bowl like configuration which canhold a second structural material 112 to be deposited as is shown inFIG. 5F according to step 161 of FIG. 5A. The second structural material112 may be any of a variety of materials depending on the purpose thecore is to serve and the properties of the material. Example materialsinclude gold (Au), silver (Ag), nickel (Ni), nickel-phosphor (Ni—P),nickel-cobalt (Ni—Co), nickel-manganese (Ni—Mn), palladium (Pd),Palladium-cobalt (Pd—Co), and tin (Sn), or the like. In some variationsof the present embodiment, the deposition of the second structuralmaterial 112 may occur in a selective manner (e.g. into voids within apatterned masking material or via a direct writing method).

FIG. 5G shows the state of the process after the deposited materialshave been planarized according to step 162 of FIG. 5A to define a layer114-1 which includes regions of a second structural material 112, andregions of sacrificial material 104 which are separated by one or moreregions of structural material 106. Structural material 106 provides ashell of structural material while material 112 provides a core ofstructural material and depending on the configuration, positioning, andinternal structure of the next layer, the core material 112 may or maynot become fully encapsulated by the shell material.

FIG. 5H shows the state of the process after multiple layers have beenformed using operations similar to those used in forming the first layer(i.e. by repeating the steps of FIGS. 5D-5G six times) but wherein thedevice design calls for the structural material located on successivelayers to have different configurations and/or locations.

In FIG. 5I, the build, or fabricated sacrificial material encaseddevice, has been transferred to and bonded (using solder or otherbonding means not shown) to a space transformer or other substrate 116as an example of step 181 of FIG. 5A.

In FIG. 5J, the formed structure, comprised of the second structuralmaterial 112 and the first structural material (i.e. coating material)106 has been released from the sacrificial material 104 and fromsubstrate 102 while remaining attached to substrate 116.

Since the coating material 106 only envelops or entraps the structuralmaterial on three sides (as shown in FIGS. 5G-5J) out of four forgeneral structure configurations, the etchant used to attack thesacrificial material must not more than minimally attack both the shellstructural material 106 and the core structural material 112 which formsthe device (e.g. a probe structure). In some embodiments, a sacrificialmaterial may be copper. Examples of electrodepositable structuralmaterials that are compatible with copper (Cu) etchants include, forexample, gold (Au), silver (Ag), nickel (Ni), nickel-phosphor (Ni—P),nickel-cobalt (Ni—Co), nickel-manganese (Ni—Mn), palladium (Pd),Palladium-cobalt, (Pd—Co) and tin (Sn).

Devices, such as probes, made primarily with a Ni or Ni alloy core and athin Au coating will have mechanical properties similar to those madepurely from Ni/Ni alloy (i.e., without a coating), but with loweroverall resistance due to the Au coating.

Devices, such as probes, made with an Au core and a Ni/Ni alloy coating,on the other hand, may have a lower spring constant than those made withNi/Ni alloy cores, but may have a particularly low resistivity.

In some alternative embodiments the compressive direction or tensionaldirection of a spring probe device when in use may be parallel,perpendicular, or at some other angle relative to the stacking directionof the layers from which the device is formed. In some embodiments, e.g.in the example of FIG. 5J, the device may be configured and fabricatedso that its primary movement direction (i.e. the active compressional ortensional direction during use) and stacking direction are largelycoincident. In some other alternative embodiments, the device (e.g.spring probe) may be configured to have a particular movement direction(e.g. compressional or tensional working direction) which may lie in theplane of the layers that are used to form the device.

Ability to vary the structural material used in forming a structure andits distribution throughout the structure leads to more flexibility inachieving a desired set of functional objectives for a particular deviceconfiguration. When an immediately succeeding layer (i.e. a next layer)includes a structural material region that is identical to, or otherwiselargely or completely overlays the structural material on an immediatelypreceding layer (i.e. the current layer), complete encapsulation ofstructural material on the current layer will occur once the firststructural material for the succeeding layer is deposited. The completeencapsulation of a second structural material for the current layerwithin one or more different shell materials (e.g. a first structuralmaterial) will occur by the base and side walls formed on the currentlayer and by the base of the deposit of the shell material on theimmediately succeeding layer. In some embodiment variations, the shellmaterial may be different on different layers as might be the corematerial. In particular, core material may be different for differentlayers and may be dependent on whether complete encapsulation occurs ornot.

In some implementations of the process of FIGS. 5A-5J, not all layers,or all portions of each layer, may be formed with two or more structuralmaterials and as such the deposition of and partial or completeencapsulation of a second structural material may be limited to only aportion of the layers (i.e. to one or more layers). Such selectiveutilization of layers, or layer portions, can provide an enhanced rangeof functional variations so that better balances of properties can beachieved, e.g. balances of conductivity, probe width, and spring force.In some alternative embodiments, the last layer may be formed with onlya first structural material so that this material completelyencapsulates the second structural material of the preceding layer anddoesn't result in a second structural material that requires a separatecapping layer.

In some implementations of the embodiment of FIGS. 5A-5J, the processmay have particularly usefulness when the width of a region of secondstructural material (i.e. the encapsulated or partially encapsulatedmaterial) is to be less than a minimum feature size for the processbeing used or when the wall thickness of the shell material is less thana minimum feature size of the process. In such cases it will not bepossible to make a mask having a width that is small enough to reliablycover the region of second structural material or may not be openable(e.g. developable in the case of photoresist) so as to form a reliableopening that can be plated into to form walls of desired width. In suchcases, the base and walls of the structural material region on a givenlayer may be formed with a first structural material by depositing itinto a region that was originally defined by an opening having muchlarger width, i.e. the width of the second material region plus twicethe width of the wall region that is being formed, which would be largerthan the minimum feature size. After deposition of the first structuralmaterial, the second structural material can be deposited to thenarrowed region thus achieving an effective deposit of the firststructure material that is narrower than the minimum features size (atleast in the wall areas) and possibly a width of deposit of the secondstructural material that is also effectively less than that of theminimum feature size.

The width of the coating in the wall regions relative to the width andthickness of the core material may be adjusted to tailor the mechanicaland electrical properties of the device. In applications where highfrequency signals will be carried, it may be desirable to use a lowresistance material (e.g. Au) as the coating material and a differentmaterial as the core material. It should also be noted that use of ahigh modulus material (e.g. Ni or NiCo) as a coating material may bringan enhanced modulus to the structure as a whole due to the largerdistance of the high modulus material from a neutral bending axis whenthe structure is put to use.

A second embodiment as discussed herein next provides a method that issimilar to the method of the first embodiment in many ways but has adifference in that each layer that includes a core material is fullyencapsulated on the bottom, sides, and top by a shell of structuralmaterial regardless of layer-to-layer configuration variations. In thisembodiment, a core along with a shell that encapsulates the bottom andsides of the core are formed in association with a single layer, or whatmay be considered a first sub-layer of the current layer, and thencapping occurs in association with an immediately succeeding dedicatedcapping layer, or what may be termed a second sub-layer of the currentlayer. As with the first embodiment, the formation of the core and thepartially surrounding shell material occurs via the use of a singlepatterning operation (e.g. using a single photoresist mask). In thisembodiment, the core material may be the same material as is used for asacrificial material or may be some other material. The core materialmay be prevented from being removed from the structure during release ofthe structure from the sacrificial material by the presence of thecompletely encapsulating structural material (i.e. the shell material).Sometimes the core material is referred to as a functional structuralmaterial in that is included in the final structure but in the absenceof the protective shell material, the functional structural materialwould have been removed during the process of releasing the structurefrom surrounding sacrificial material as the etchant that removes thesacrificial material would have also removed the functional structurematerial. In this embodiment, individual layers may be viewed asindividually planarized thicknesses of structural and sacrificialmaterials in which case complete encapsulation of core material requirestwo layers with the top layer being a capping layer. Alternatively inthis embodiment, individual layers may be viewed (i.e. when core regionsexist) as compound layers that include at least a first lower sub-layerportion and a upper, second sub-layer portion. As used hereafter “layer”by itself will refer to a non-compound layer while “compound layer” willrefer to a layer that is made up of a plurality of vertically stackedsub-layers. In some variations of this embodiment, a structure may beformed from one or more compound layers and one or more non-compoundlayers. As with the first embodiment, in this embodiment, the shellstructural material forms upward facing pockets on the first sub-layerportions (i.e. facing away from previously formed layers) for holdingthe core structural material. In some variations of this embodiment,multiple masking operations may be used during the formation ofindividual non-compound layers and compound layers to yield structureswith enhanced configurations or properties.

FIG. 6A provides a flowchart for a process according to a secondembodiment of the invention where the structure is formed from at leasta first structural material that provides a shell material that fullyencapsulates at least a second structural material that is a corestructural material and may also be a functional structural material andwherein some layers used in forming the structure are compound layersformed of a plurality of stacked sub-layers wherein a first sub-layer ofeach compound layer provides an up-facing shell structural material anda core structural material and a second sub-layer of each compound layerprovides a capping structural material for the core structural materiallocated on the immediately preceding layer, and wherein the sidewalls ofthe shell may be narrower than a minimum feature size associated withthe formation of the layer containing the walls.

FIG. 6B provides a flowchart for the same process as set forth in FIG.6A with the exception that instead of viewing the up-facingencapsulating shell material and the core material as being formed on afirst sub-layer and a capping material being formed on an immediatelysucceeding second sub-layer of the compound layer, each fully planarizedlevel of structural and sacrificial material is considered a separatelayer and thus up-facing shell and core material formed on a particularlayer are followed by the formation of a corresponding capping layer.

The processes of FIGS. 6A & 6B have many steps in common with theprocess of FIG. 5A. In particular, steps 251-258 and 280-285 of FIGS. 6A& 6B are substantially identical to steps 151-158 and 180-185 of FIG.5A, respectively, and will be minimally discussed hereafter as thecomments provided with regard to the FIG. 5A steps are believed equallyapplicable to the corresponding reference numbers in FIGS. 6A and 6B.Step 258 uses the expression a “1^(st) sub-layer of the current compoundlayer” in association with FIG. 6A and just “current layer” inassociation with FIG. 6B. For the reasons noted above, the steps areotherwise substantially identical.

Steps 260-A to 262-A of FIG. 6A are similar to steps 160-162 of FIG. 5Abut instead of applying to an “n” layer as a whole they apply to theformation of a first sublayer that forms a portion of the currentcompound layer “n”. Steps 265-A to 267-A have no equivalents in theprocess of FIG. 5A. Step 265-A calls for the forming of a part of asecond sub-layer of current compound layer “n” by selectively depositingone of a structural material or a sacrificial material while step 266-Acalls for the deposition of the other of the sacrificial or structuralmaterial to form another part of the second sub-layer of compound layer“n”. Step 267-A calls for the planarization of the materials depositedin steps 265-A and 266-A to set a boundary level for the secondsub-layer of current compound layer “n”. As a whole, steps 265-A to267-a result in the capping of the core material region of the firstsub-layer with a genuine structural material. In variations of thisembodiment the first and second sub-layers may have the same heights orthey may have different heights. Unlike the first embodiment, wherecomplete encapsulation only occurs under certain geometric constraints,in this second embodiment, complete encapsulation is ensured by theformation of the second sub-layer which selectively places cappingmaterial on a first sub-layer containing an up-facing shell material andassociated core material. Many of the alternatives discussed above inassociation with the first embodiment are also applicable to thisembodiment.

As noted above, the flowchart of FIG. 6B sets forth a process that issubstantially identical to the process of FIG. 6A with the exceptionthat different terminology is used to describe what is being created. Inparticular in the process of FIG. 6B, instead of considering shell/corematerial sub-layers and subsequent capping sub-layers as sub-layers of asingle compound layer “n’, this variation considers the shell/corematerial sub-layer to be a layer and the subsequent capping layer to bean adjacent but distinct layer. Due to this two-layer vs. one compoundlayer distinction, the method of FIG. 6B includes an additional step264-B which causes an incrementing of the layer number “n” aftercompletion of steps 260-B-262-B which are similar to steps 260-A-262-Ain their effective result. Steps 265-B to 267-B are likewise similar tosteps 265-A-267-A of FIG. 6A in their effective result.

FIGS. 6C-6N schematically depict side views of various states offormation of an example device (e.g. a conductive probe for testingintegrated circuits) formed by the process of FIG. 6A or 6B.

FIGS. 6C-6N schematically depict side views of various states during theformation of a device (e.g. a probe) being formed by a process accordingto the second embodiment of the invention where the device is formedfrom a core material and a material that completely defines the bottom,sides, and top surfaces of each layer of the probe where each layer, inthe terminology of FIG. 6A is a considered a compound or multi-partlayer that includes a plurality of sub-layers. As illustrated eachcompound layer includes a first sub-layer portion and a second sub-layerportion. The first sub-layer portion includes an encapsulatingstructural material in the form of a shell that bounds the bottom andsides of a core structural material region where the core structuralmaterial may be a functional structural material (i.e. a material thatwould be removed with removal sacrificial material or significantlydamaged by the removal of the sacrificial material if a releasingetchant had access to it) that occupies at least a portion of the regiondefined by the bounding walls of the encapsulating (shell) structuralmaterial. The second sub-layer portion is formed above the firstsub-layer and provides a selective region of a capping material forbounding the top of the encapsulated material to trap it within theshell of the first structural material (or in some variations with ashell of a plurality of structural materials that are not attacked by anetchant that is used in the release of the structure from sacrificialmaterial). Looked at from the perspective of FIG. 6B, this embodimentbuilds up a structure from a plurality of adhered layers where layersthat contain a core material are followed by the formation of cappinglayers that complete the entrapment or encapsulation of the corematerial within a shielding or shell of a different structural material.

In this second process embodiment a two-material device (e.g. a probe orbody of a probe) may be formed while using only two materials in thebuild process (i.e. a first structural material and a material thatfunctions as a sacrificial material at times and as a second structuralmaterial at other times, i.e. a functional structural material). In somevariations of this embodiment one or more additional materials may beincluded, for example as a hardened tip material This may beaccomplished by fully encapsulating what would otherwise be asacrificial material within a surrounding envelope or shell of a firststructural material in regions that are to form solid parts of astructure.

In some variations of this embodiment, the devices may be formed in abatch manner (e.g. multiple devices may be formed simultaneously or inseries on a common substrate) and then separated from the sacrificialmaterial but not separated from the build substrate. In still otherembodiments, the device may be separated from the build substratewithout first bonding them to another substrate. The devices may be usedas released or bonded to other substrates, components, or the like afterinitial separation from the build substrate which may occur before orafter release from the sacrificial material. In some variations of thisembodiment, attachment to other components or substrates may occurbefore or after release from the build substrate.

In FIG. 6C, the state of the process is illustrated after a temporarysubstrate 202 is provided.

In FIG. 6D, the state of the process is illustrated after an optionallayer of a sacrificial material 204 (e.g. Cu) has been applied ordeposited and planarized. This layer of sacrificial material 204 may beapplied to act as a means for readily releasing the devices orstructures from the build substrate.

In FIG. 6E, the state of the process is shown after a second level ofsacrificial material (e.g. Cu) has been selectively deposited and anypatterned mask used in the selective deposition removed. An alternativeto this selective deposition step, for this embodiment and for theembodiment of FIGS. 5A-5I, is to blanket deposit the sacrificialmaterial and then selective etch material away (e.g. via an opening in apatterned mask).

In FIG. 6F, the state of the process is shown after a coating materialor structural material 206 is deposited as a thin shell or coating. Insome implementations of the present embodiment, the same structuralmaterial may be used on a plurality of adhered layers or differentstructural materials may be used on different layers. Examples ofstructural materials include those noted above with regard to FIGS.5B-5J. The first structural material may be blanket deposited to form acoating of a desired thickness that is less than the layer thickness inthe base area of the shell and in the horizontally extending sidewallregions of the shell as well. In some implementations of thisembodiment, thicknesses of such coatings may similar to the examplethicknesses noted above with regard to FIGS. 5B-5J. As with variationsof the first embodiment, in variations of this embodiment, the firststructural material or coating material may be deposited in a selectivemanner. The thickness of the deposited structural material 206 is madeless than the intended thickness or first sub-layer so that a quantityof what would otherwise be the sacrificial material 204 may be depositedinto the remaining portion of void 208 to form a second structuralmaterial 212 (see FIG. 6H) within the pocket of the first structuralmaterial 206. The deposition of the sacrificial material 204 thatbecomes functional structural material 212 is shown in FIG. 6G (as 204)and is shown in FIG. 6H (as 212) after planarization completes formationof the first sub-layer (SL1) for a first compound or multi-part layer(CL1). FIG. 6I depicts the state of the process after a deposition of asacrificial material 204 forms part of the second sub-layer (SL2) forthe first compound or multi-part layer (CL1). As the sacrificialmaterial 204 of SL2 will eventually undergo a planarization operationthat will set the height or upper boundary of SL2, SL2 and CL1 aredepicted in FIG. 6I as having boundary levels below the height of thedeposited material 204. FIG. 6J shows the state of the process after anadditional coating of structural material 206 is blanket deposited tofill the void formed in the sacrificial material 204 for SL2 of CL1while FIG. 6K shows the state of the process after planarizing sets theheight of the deposited structural material 206 and sacrificial material204 of the second sub-layer (SL2) of the first compound layer (CL1) to aheight matching the desired boundary level of the second sub-layer (SL2)and the first compound layer (CL1) as a whole.

In FIG. 6L, in terms of the method of FIG. 6A, the state of the processis shown after multiple compound layers (CL1-CL7) have been completed.Every compound layer is formed from a first sub-layer and a secondsub-layer, where the first sub-layers provides for an encapsulatingstructural material and a partially surrounded (i.e. on the bottom andsides) functional structural material while the second sub-layersprovide for capping of functional structural material associated withthe immediately preceding first sub-layer that is bounded by theencapsulating structural material of that immediately preceding firstsub-layer. Alternatively considered, FIG. 6L shows the state of theprocess after 14 layers of the structure have been formed withalternating layers with odd ones providing functional structuralmaterial within pockets of a different structural material and even onesproviding a capping layer of the different structural material.

In this embodiment, the capping layers, or second sub-layers, are formedfrom at least one structural material and at least one sacrificialmaterial that are planarized. In this example, the formation of theadditional compound layers occurs via the same processes used in formingthe layer of FIGS. 6E-6K. The last layer of the structure may or may notbe followed by the formation of a complete capping layer (L14) or secondsub-layer (CL7) as shown in FIG. 6L. Instead of a complete final cappinglayer or second sublayer, a selective deposition of the structuralmaterial may be used which in turn may or may not be followed byplanarization.

In FIG. 6M, the state of the process is shown after the structure,substrate, and surrounding sacrificial material have been transferred toand bonded to a space transformer 214 or other permanent substrate (bysolder or other bonding means not shown).

In FIG. 6N, the non-encapsulated sacrificial material 204 has beenseparated from the structure leaving behind the shell of structuralmaterial 206 that encapsulates the functional structural material 212.As with the embodiment of FIGS. 5A-5I, the thickness of the structuralmaterial relative to the thickness of the core sacrificial material 112may be adjusted to tailor the mechanical and electrical properties ofthe structure.

It is important to ensure that no gap exists in the structural materialthat surrounds a functional structural material 212 (i.e. the “core”sacrificial material as distinguished from the sacrificial material 204that will eventually be removed). Such a gap could allow etching of thefunctional structural material 212 or core sacrificial material 212.Since the only function of the second sub-layer is as a cap, the secondsub-layer SL2 may be thinner than first sub-layer and in fact in someembodiments its thickness may approximate the thickness of the depositedencapsulating material used in forming the sub-layer.

In some variations of this second embodiment, instead of there beingonly a first (i.e. encapsulating) structural material and a second (i.e.encapsulated structural material) used during the formation of a firstsub-layer, more than two structural materials may be deposited toprovide more than one encapsulating and/or encapsulated material. Instill other variations, structural material regions may be filled withdifferent encapsulating materials and/or encapsulated materials and evensome structural material regions formed only of a single structuralmaterial (e.g. a primary structural material). In some embodiments, theorder of depositing sacrificial and structural materials may be variedfrom layer to layer.

In variations of this embodiment, instead of the cap, or structuralmaterial on the second sub-layer, being made to be identical inconfiguration to the structural material region of the previous layer,or the corresponding first sub-layer, it may be made to extend beyondthe region of the structural material if such an extension exists in thesubsequent layer or subsequent first sub-layer. However, as noted abovewith regard to the application of the first embodiment to the formationof two identical layers, the formation of the subsequent shell/corelayer will automatically cap the second structural material on aprevious layer without need for a separate capping layer or secondsub-layer and as such recognition of such situations may allow areduction in the number of layers or sub-layers that need to be formedwhile still achieving complete encapsulation.

In a variation of this embodiment, the plating of the capping material(i.e. structural material on a subsequent layer or on the secondsub-layer) may be by pattern-plating of the structural material, insteadof by pattern plating the sacrificial material, followed by blanketplating of the structural material. In some variations (e.g. when thecap is made thin enough, e.g. 1-2 microns in thickness, the plating ofthe sacrificial material and the planarizing of the cap layer may becomeunnecessary. The slight topography induced by patterned plating of thecapping material may not significantly interfere with fabrication of anext layer. In such variations the plating of the capping material maybe considered part of the formation of the previously layer that takesthe otherwise planar layer slightly out of planarity but at a level thatdoes not impact the normal formation of a next layer. This variation is,in part, the subject of the third embodiment that will be discussedhereafter.

In some variations of this embodiment, the deposition of cappingmaterial (i.e. structural material) during the formation of a cappinglayer may not result in the capping material being deposited over allregions of the preceding first sub-layer that contained the functionalstructural material. Instead the deposition of capping material may belimited to only those regions where no structural material exists on thefirst sub-layer of the next compound layer. In such a case, theadditional structural material needed may be deposited during formationof this next layer. In still further alternatives, other cappingmaterial deposition patterns can be advantageously defined.

The third embodiment set forth herein is a modified version of the firstand second embodiments. It modifies the first embodiment in that itprovides full encapsulation of core material associated with theformation of individual layers and it modifies the second embodiment inthat the capping of the core material is not provided by formation of acomplete “capping” layer as a second sub-layer. In this embodiment,after formation of a layer containing a core material and a shellmaterial that bounds the bottom and sides of the core material, aselective deposition of structural material, which may be relativelythin compared to the overall layer thickness, is provided to cap thecore material and then a next layer of structural material andsacrificial material is formed over the bump made by the cap. In thisembodiment, the capping material is not planarized in conjunction with asurrounding quantity of sacrificial material as it would be as part of asecond sublayer. As with the first embodiment not all layers needinclude deposits of core structural material.

Like the method of the second embodiment, the full encapsulation resultof this embodiment may allow the core structural material to be selectedfrom a broader group of materials. As discussed above, the ability ofthe core structural material to withstand attack from sacrificialmaterial etchants becomes moot if the coating or shell material providessuch protection. For example, copper may be used as a structuralmaterial with a gold coating while nickel may be used as a sacrificialmaterial since etchants that may be used to remove nickel do not attackgold but do tend to attack copper. The encapsulation may serve one ormore of the following purposes: a) protect the core structural materialduring etching of sacrificial material; b) improve interlayer adhesion;c) decrease interlayer resistance; and d) prevent oxidation or othercorrosion of surfaces of the core structural material. As with theprevious embodiment, the method of this embodiment allows a singlematerial to act as a core structural material and as a sacrificialmaterial simultaneously. This embodiment may have particular usefulnessfor applications where electrical conductive is important such as in RFapplications and in microprobe applications.

FIG. 7A provides a flowchart for a process according to the thirdembodiment of the invention where the structure is formed from at leasta first structural material that provides a shell material that fullyencapsulates at least a second structural material that is a corestructural material and may also be a functional structural material andwherein some layers are formed with an up-facing shell structuralmaterial and a core structural material located within a pocket formedby the shell material, wherein an immediately succeeding layer includesan initial deposition of a structural material that caps the corematerial and has a relatively thin height compared to the layerthickness, wherein continued formation of the immediately succeedinglayer occurs according to the intended configuration of that layeritself, and wherein the sidewalls of the shell may be narrower than aminimum feature size associated with the formation of the layercontaining the walls.

The process of FIG. 7A has number steps that are substantially identicalto steps in the process of FIGS. 5A, 6A and 6B. In particular, steps351-355 and 380-385 of FIG. 7A are substantially identical to steps251-255 and 280-285 of FIGS. 6A & 6B, respectively, and are alsosubstantially identical to steps 151-155 and 180-185 of FIG. 5A,respectively, and will be minimally discussed further herein as thecomments provided with regard to the FIG. 5A steps are believed equallyapplicable to the corresponding reference numbers in FIG. 7A.

Steps 358-362 are very similar to steps 258-A-262-A of FIG. 6A and258-B-262-B of FIG. 6B as discussed above and result in the formation ofa layer that includes an up-facing shell of structural material thatbounds the base and sides of a core material. As compared to the processof FIG. 6B steps 264-B to 267-B are replaced, in FIG. 7A, with a singlestep 368 that calls for the deposition of a relatively thin selectivelylocated cap of structural material to complete the encapsulation of thecore material deposited in association with the immediately precedinglayer. This cap of structural material is intended to occupy a thinportion of the next layer to be formed. In some variations of thisembodiment, the structural material of Step 368 may or may not beplanarized, and the planarization may include planarization of anyremaining masking material which may thereafter be completely removed.After this step the process moves forward to enquiry step 380 whichdetermines whether just completed layer “n” and the overlaying cap wasthe last layer of the structure or whether the process should loop backto 354 for the formation of additional layers.

FIGS. 7B-7I schematically depict side views of various formation statesthat occur during the formation of a sample structure according to thethird embodiment of the invention. In this embodiment, a shell orsecondary structural material fully encapsulates each layer of a core orprimary structural material. As with the other embodiments discussedherein, only the major steps or operations involved are explicitly setforth. It is understood that those of skill in the art may elect toperform additional standard or common steps such as cleaning operations,activation operations, surface roughening operations, inspectionoperations, and the like. Though, as with the other embodiments, thedescription to follow deposits the sacrificial material first during theformation of a layer containing shell and core material, it isunderstood that alternative embodiments are possible that would depositthe structural material first.

FIG. 7B depicts the state of the process after a patterned deposition ofa sacrificial material 302 occurs on a substrate 300. This may beperformed using standard lithography steps through which a photoresistpattern is created. In this embodiment, the deposition of sacrificialmaterial preferably occurs by electrodeposition. The sacrificialmaterial may, for example, be copper or nickel in thicknesses rangingfrom 0.5 μm to 30 μm. However, in alternative embodiments other metalsand different deposition thicknesses may be used.

FIG. 7C depicts the state of the process after a thin blanket depositionof encapsulating material 304 (e.g. a secondary structural material)occurs. This step deposits a relatively thin, conforming layer ofmaterial (e.g. gold, nickel, nickel cobalt, palladium). In thisimplementation of the method, the deposit or coating may be applied bysputtering, for example at a thickness of about 500 Å. In otherembodiments other materials may be used and other thicknesses may beused (e.g. from 50 Å to 2 μm). In other embodiments, other depositiontechniques may be used and much thicker depositions obtained. Otherdepositions methods include, for example, evaporation, electrolessdeposition, electrolytic deposition, or even electroplating. In someembodiment variations, it may be advantageous to deposit an adhesionlayer before or after application of the encapsulating material. Such anadhesion layer may have a thickness ranging from, for example, 10 Å-100Å and may be of Ti or Cr. In still other alternative embodiments, othermaterials may alternatively or additionally be deposited, for example toact as diffusion barriers. For example, before or after a goldencapsulant is deposited (depending, for example, on which side copperis to be located), 10 Å to 100 Å of nickel may be deposited to act as abarrier to prevent the diffusion of the copper into the gold.

FIG. 7D depicts the state of the process after a blanket deposition ofstructural material 306 (e.g. copper, nickel, nickel cobalt, orpalladium) occurs. The deposition may occur via an electrodepositionprocess or it may occur through other means (e.g., sputtering,evaporation, etc.). In some embodiments, a typical range of depositionthickness may be from 0.5 μm to 30 μm or more. As noted above, in somealternative embodiments, the structural and sacrificial materials may bethe same (e.g., copper may act as a sacrificial material in general andas a functional structural material when encapsulated by nickel and/orgold).

FIG. 7E depicts the state of the process after planarization occurs.This planarization step may take different forms, for example (1)lapping with a free abrasive, (2) lapping with a fixed abrasive, (3)grinding, or (4) fly cutting. This planarization may occur in one ormore steps (e.g. in a progressive fashion using different abrasives orcutting methods) and may include intermediate height and parallelismmeasurements as, for example, taught in U.S. patent application Ser. No.11/029,220, now U.S. Pat. No. 7,271,888.

FIG. 7F depicts the state of the process after a thin patterneddeposition of encapsulating material 304 occurs over the regions on thejust planarized layer. A mask for performing the patterned depositionmay be obtained photolithographically from development of a photoresistusing a photomask that has substantially the inverse pattern to thatused in operation leading to FIG. 7B. If on the other hand, thestructural material is pattern deposited then the same pattern may beused for creating photoresist masks for both depositions. In stillanother variation, if a positive photoresist is used for one of thedepositions and a negative resist used for the other, it may be possibleto use the same photomasks to produce photoresist masks for bothdepositions even though one applies to the deposition of sacrificialmaterial and the other applies to the deposition of structural material.The amount deposited should be kept as thin as possible (consistent withother objectives). In some alternative embodiments, excess thickness ofthe encapsulant, may be removed by fly cutting or another planarizationprocess. If necessary, masking material could remain during theplanarization process or additional sacrificial material could bedeposited to help protect the sidewalls of the encapsulation materialfrom damage during abrasive planarization and thereafter removal of themasking material could occur.

FIG. 7G depicts the state of the process after the operations of FIGS.7B-7F are repeated two more times so as to produce the desiredstructure. In some embodiment variations, a structure may be formed inthree layers as illustrated in this example, but in many situationsadditional layers may be required (e.g. a total of 5 to 10 to 20 or even40 layers or more may be necessary to form a structure of desired heightand configuration. In this embodiment, it is assumed that the thicknessof the encapsulant that is located on top of each layer is thin enoughto not interfere with operations used in forming the next layer. Assuch, in embodiments where photoresist will be used as a maskingmaterial, it is assumed that photoresist material can be applied overthe transition from sacrificial material to encapsulating material andthat patterning and development can occur without undue interference bythe stepped surface. In the illustration of FIG. 7G, the coating formedto cap off core material on a previously formed layer, results in somevisual distortion of the core material thicknesses for any succeedinglayer.

FIG. 7H depicts the state of the process after sacrificial material 302is removed, e.g. by chemical etching. In this example, the structure(s)are shown as being formed in direct contact with a substrate while insome variations, the structures may actually be separated from thesubstrate by a layer of sacrificial material so that separation of thestructure(s) from the substrate can readily occur. In still othervariations, separation of the structures from the substrate may occur inother ways.

FIG. 7I depicts the state of the process after an optional process stepcauses inter-diffusion of the shell and core materials to form amodified coating 308. In some embodiment variations, it may be desirableto produce this inter-diffusion result while in other embodiments it maybe something to be avoided (e.g. by using barrier layers and/orselection of substantially non-inter-diffusing material pairs, e.g. suchas nickel and copper, or the like. If inter-diffusion is desired, thoseof skill in the art can empirically determine most appropriate treatmentconditions and application times based on their objectives, thematerials involved, and the like. In some embodiment variations, forexample, desirable material properties may be obtained by heating to600° C. for fifteen minutes in a reducing atmosphere.

As with the previously presented embodiments, numerous additionalvariations of this embodiment are possible. Some of these variations mayinvolve the alternatives associated with previously presentedembodiments while others may involve some of the features presented aspart of those embodiments themselves. An examples of such variationsincludes replacing the thin secondary structural material with a thickerdeposition of a shielding structural material that remains thin enoughto provide a recess within a single layer for receiving a corestructural material that may or may not be a functional structuralmaterial.

A fourth embodiment of the invention provides method for processinglayers identical to that of the first embodiment but with certaingeometric constraints placed on the structure to be formed. Inparticular each layer that includes an up-facing shell of genuinestructural material that is filled with a core of functional structuralmaterial has its core material encapsulated by the formation of the nextlayer whether the next layer is formed as a core/up-facing shell layeror as a layer formed from a single genuine structural material. As such,in this embodiment, any layer “n” that contains a core material will befollowed by the formation of an immediately succeeding layer “n+1” thathas a lateral configuration (i.e. a configuration in the plane that isperpendicular to the build axis upon which layer stacking occurs) thatsufficiently overlays the lateral configuration of the core andsurrounding shell material of layer “n” so that its formation fromstructural material will provide sufficient capping of the layer “n”. Toprovide adequate encapsulation a minimum overlap delta, δ, ofshell-quality structural material must occur from layer-to-layer and assuch, layer “n+1” must not have a configuration that provides layer “n”with an up-facing feature that would reduce the overlap to less thandelta. Of course on layers “n” where only a single structural materialis to exist or on layers “n” where complete encapsulation of structuralmaterial is not necessary, the configuration of layer “n+1” is not ofsignificance.

FIG. 8A provides a flowchart for forming a structure according to afourth embodiment of the invention, which is substantially identical tothat of FIG. 5A but with the simplified structure requirement notedabove and with the core material being a functional structural material.The steps of the process of FIG. 8A are labeled with reference numberssimilar to their corresponding steps in FIG. 5A with the exception theybegin with 400 instead of 100. All or a portion of the layers are formedusing a core material that may be a functional structural material thatis encapsulated by a shell material wherein the bottom and sides of theshell are formed for an nth layer as part of the nth layer while the topof the shell for the nth layer is formed by a capping material (e.g. thestructural shell material) that is effectively provided by the formationof the layer “n+1”. As with the other embodiments, the sides of theshell may be narrower than a minimum feature size associated with theformation of the layer. This narrowing capability, as in the otherembodiments, comes from the fact that the width of the side walls is notdictated on all sides by edges of a masking material or sacrificialmaterial that forms a void that is to be completely filled but insteadis based on only partially filling of a conductive void. Since the voidhas conductive walls, the buildup of deposited material not only growsupward from the bottom (to form a base) but also from the sides to formwalls. When the base thickness is sufficient, but less than the layerthickness, and the wall width is sufficient, deposition ceases anddeposition of a different material (i.e. a core material) can begin.

FIGS. 8B-8J illustrate various states of the process of FIG. 8A asapplied to the formation of a particular example structure. In thisexample the structure is formed from five layers while laying on itsside with the cross-sectional figuration of the second layer beinglarger than that of the first layer (at least along the cut as shown),that of the third layer matching that of the second layer, and with thatof the fifth layer matching that of the fourth layer which in turn issmaller than that of the third. In this example, the first, second, andfourth layers can be formed with a genuine structural material formingthe sides and bottom of a shell that in turn holds a functionalstructural core material. The core material on each of the first, secondand forth layers becomes fully encapsulated by a structural materialthat forms the immediately succeeding layer.

FIG. 8B shows the state of the process after a substrate 402 is coveredwith a release layer of sacrificial material 404.

FIG. 8C shows the state of the process after a photoresist 403 isdeposited and patterned to form a mask around which a layer ofsacrificial material is deposited (masking material, additionalstructures being formed, or other deposition inhibiting material aroundthe edges of the build are not shown) while FIG. 8D shows the state ofthe process after the sacrificial material and photoresist of the firstlayer are optionally planarized (typically to a height that is somewhatabove the boundary level for the current layer).

FIG. 8E shows the state of the process after the photoresist is strippedso as to leave a void 408 that can receive structural material.

FIG. 8F shows the state of the process after a first, shell, and genuinestructural material 406 is deposited to a depth of less than one layerthickness which causes formation of a base and sidewalls for a shellstructure.

FIG. 8G shows the state of the process after deposition of a second,core, and possibly functional structural material 412.

FIG. 8H shows the state of the process after the first layer iscompleted by the planarization of the sacrificial material and the twostructural materials.

FIG. 8I shows the state of the process after formation of an additionalfour layers (L2-L5) some of which are formed using the steps illustratedin FIGS. 8C-8H while others use different steps (e.g. the stepsillustrated in FIGS. 8C-8F and 8H with the deposition of FIG. 8F beingcontinued to a height at least as great as the layer thickness.

FIG. 8J illustrates the state of the process after the five layerstructure, having two regular layers and three shell/core layers, hasbeen released from the sacrificial material and from the substrate.

As with the other embodiments discussed above numerous variations ofthis process are possible and include, for example, variations thatincorporate additional materials into shell/core layers, variations thatadd additional materials to non-shell/core layers, variations thatmodify the layer thickness between shell/core layers and non-shell/corelayers, variations that have fewer layers (e.g. as few as two) andvariations that have more layers as many as 10, 20, 40 or even more,variations that use a non-conductive core material (that may be coatedwith a seed layer to allow deposition of additional layers according tothe methods set forth in some of the patents and applicationsincorporated herein by reference), variations that include a conductivecore material and a non-conductive shell material on at least somelayers, variations that leave the formed structure attached to the buildsubstrate or transferred to a different substrate, variations thatextend core material to more than one layer when allowed by the geometryof the structure being formed, variations that form some layers of somestructures with more than one shell/core region, variations that reversethe order of structural material and sacrificial material deposition onat least some layers, variations that use a non-conductive sacrificialmaterial, variations that mix the shell/core formation method of theother embodiments with those of this embodiment, and the like.Additional variations will be understood by those of skill in the artupon review of the teachings herein.

A fifth embodiment of the invention provides a method for processinglayers to create encapsulated quantities of core material within asingle layer where a partially encapsulating shell material provides adownward facing configuration. As with the first four embodiments, thesteps of this process do not require the use of mask dimensions, orvoids, that extend through masking material that would violate anyminimum feature size constraints that exist for the build process. Aswith the previous embodiments, the core and shell defining steps of thepresent method need not be applied during the formation of each layer.In fact in some implementations the steps of this embodiment may be usedon layers immediately following layers that used the shell/coreformation steps of any of the first-fourth embodiments. Such combinedusage can yield structures with core regions that are joined acrosslayer boundaries. In some other variations of this embodiment, theshell/core forming steps of this embodiment may be applied to the capforming steps of the second or third embodiments. In one such variation,the capping layers of the second embodiment would be formed prior toforming the corresponding shell/core layers of the present embodiment.In another such variation, the capping material of the third embodimentwould be formed on the bottom of the layer before performing theshell/coring layer steps of the present embodiment so as to providecomplete encapsulation within a single layer. In the above notedvariations the capping material is located below the cores that theyencapsulate.

FIG. 9A provides a flowchart for forming a structure according to afifth embodiment of the invention, which unlike the first-fourthembodiments, creates a down-facing shell that encapsulates the sides andtop of a core material which may be used to create structures withenhanced properties. With regard to the process applied on a currentlayer, the core material is not encapsulated on its lower side, unlesssuch encapsulation is supplied by structural material applied in otherpreceding steps or by the immediately preceding layer. As with the otherembodiments, the shell side walls may be narrower than a minimum featuresize associated with the formation of the given layer.

Like the other embodiments, some of the steps of the embodiment of FIG.9A are similar to those of the previous embodiments and are labeled withsimilar numbers with the exception that the series number now startswith 500 instead of 100-400. In particular, steps 551-555 and 580-585are similar to the corresponding steps in the earlier embodiments withthe exception that the enquiry of step 554 is concerned about whetherthe current layer “n” is to be formed with a down-facing shell materialinstead of an up-facing shell material. In the present embodiment steps569, 570 and 572-576 provide the unique down-facing shell/core materialcombination.

Step 569 follows step 554 when the answer to the enquiry of step 554 is“yes”. Step 569 calls for the patterning of deposit of a functionalstructural material (e.g. sacrificial material) to a location that willform an encapsulated part of the structure wherein the thickness iseither less than the layer thickness of the current layer or will bemade less than the layer thickness after a planarization occurs. Thisstep assumes that the width of the functional structural material thatis deposited is not less than the minimum feature size of the currentlayer, or at least of a layer of the thickness required for the heightof the structural material that needs to be deposited, since a mask ofappropriate height and with voids of appropriate lateral dimensions mustbe created.

Step 570 follows step 569 and calls for the optional planarization ofthe deposited functional structural material, to a height that places itbelow a boundary level for the current layer so that it may beencapsulated by another structural material (i.e. shell material) to bedeposited in a later step.

Step 572 follows step 570 and calls for removal of any masking materialinvolved in the patterned deposition of the functional structuralmaterial and the re-patterning of a masking material to leave voidsadjacent to the sides of the functional structural material where thevoids between the functional structural material and the maskingmaterial have a width equal to a desired width of a structural materialto be deposited.

Step 573 follows step 572 and calls for the deposition of a 1^(st)structural material (shell material) to a thickness at least as great asthe desired thickness of the “n” layer so as to form the encapsulatingsidewalls and the encapsulating top cap.

Step 574 follows step 573 and calls for removing any masking materialinvolved in the patterned deposition of the shell structural materialdeposited in Step 573.

Step 575 follows step 574 and calls for deposition (e.g. blanketdeposit) of at least one sacrificial material.

Step 576 follows step 575 and calls for the planarization of thedeposited materials to set a boundary level for current layer

From step 576 the process moves to the enquiry of step 580 and eithercontinues on to the post-layer formation steps 581-584 if the last layerwas just completed or loops back to step 554 after the layer numberincrementing step of 585.

FIGS. 9B-9K illustrate various states of the process of FIG. 9A asapplied to the formation of a particular sample layer of a structurewhich has a lateral size similar to that of a previous layer on which itis formed with the exception that the previous layer (according to thisillustration) was formed using an up-facing shell and core method (suchas that used in one of the first-fourth embodiments) and such that acore material region is formed starting in and extending from animmediately preceding layer and extending into and ending in the currentlayer.

FIG. 9B shows the state of the process after a previously formed layerL(n−1) containing a shell region of a structural material 506, a coreregion of a structural material 512, and region of sacrificial material504 is provided with a photoresist 503-1 that is patterned to form amask with voids into which a current layer “n” of core structuralmaterial, e.g. functional structural material, may be deposited.

FIG. 9C shows the state of the process after the core structuralmaterial 512 is deposited to a height greater than a desired height forthe core material in anticipation of a subsequent planarization processthat will bring the effective height down to a desired height. In somevariations of this embodiment, the height of deposit of the corematerial may be set to the desired height which may eliminate the needfor the subsequent planarization process.

FIG. 9D depicts the state of the process after the structural material512 and photoresist 503-1 of the current layer “n” is planarized to adesired height which is less than the height or thickness of layer “n”.

FIG. 9E shows the state of the process after the photoresist 503-1 isstripped.

FIG. 9F shows the state of the process after additional photoresist503-2 is applied and patterned to form a void containing the corematerial and a surrounding void where a genuine structural material 506may be deposited to form the walls of the shell.

FIG. 9G shows the state of the process after deposition of the genuinestructural material 506 to a height that forms walls around the corestructural material 512 and forms a cap over the core material. Theheight of deposition of the shell material is at least as great as thethickness of the layer “n” that is being formed.

FIG. 9H shows the state of the process after the photoresist 503-2 isstripped in preparation for depositing a sacrificial material. In somevariations of this embodiment, the deposited structural material 506 maybe planarized before removal of the photoresist but this is generallynot considered necessary as it will undergo subsequent planarizationanyway.

FIG. 9I shows the state of the process after deposition of a sacrificialmaterial 504 raises the net height of material for all regions of thecurrent layer “n” to at least the desired thickness, boundary height, orlevel of the current layer “n”.

FIG. 9J shows the state of the process after the sacrificial material504 and the structural material 506 have been planarized to a heightthat sets the thickness of layer “n” (i.e. is within a desired toleranceof the intended layer thickness or upper boundary level of the currentlayer “n”).

FIG. 9K shows the state of the process after removal of the sacrificialmaterial from the two layers “n−1” and “n” forming the structure andrelease from any build substrate (not shown in this series of FIGS.). Inthis illustration it can be seen that core material on the “n−1” layerand core material on the “n” layer are joined together and that thiscombined core region is encapsulated by the shell material deposited inassociation with the “n−1” layer and in association with the formationof the “n” layer. In other variations of this embodiment additionallayers could have been added if required to complete formation of thestructure and additional layers could have been formed before the “n−1”layer. In still other variations, the overall configuration andshell/core figuration, if any, of layer “n−1” could have been differentthan that indicated.

As with the other embodiments discussed above, numerous variations ofthis process are possible and include, for example, variations thatincorporate additional materials into shell/core layers, variations thatadd additional materials to non-shell/core layers, variations thatmodify the layer thickness between shell/core layers and non-shell/corelayers, variations that have more layers as many as 10, 20, 40 or evenmore, variations that use a non-conductive core material (that may becoated with a seed layer to allow deposition of additional layersaccording to the methods set forth in some of the patents andapplications incorporated herein by reference), variations that includea conductive core material and a non-conductive shell material on atleast some layers, variations leave the formed structure attached to thebuild substrate or to a different substrate that is attached after layerformation, variations that extend core material to more than one layerwhen allowed by the geometry of the structure being formed, variationsthat form some layers of some structures with more than one shell/coreregion, variations that reverse the order of structural material andsacrificial material deposition on at least some layers, variations thatuse a non-conductive sacrificial material, variations that mix theshell/core formation method of the other embodiments with those of thisembodiment, and the like. Additional variations will be understood bythose of skill in the art upon review of the teachings herein.

A sixth embodiment provides a method for providing core material thatextends completely through a given layer, i.e. continuing core regions,while still providing for the formation of shell material wallthicknesses that are less than the minimum feature size without usingmask features or voids that are smaller than that allowed by the minimumfeature size. In some implementations of this embodiment, the layerscontaining continuing core regions may be preceded by other continuingcore region layers or by up-facing core configurations, as produced bythe first-fourth embodiments, and be proceeded by other continuing coreregion layers or by down-facing core configurations as produced by thefifth embodiment. In still other embodiments, layers containingcontinuing core regions may be bounded from below and/or above bynon-shell/core layers, bounded from below and/or above by cappingstructures such as those of the third embodiment, capping layers such asthose of the second embodiment, or bounded from below and/or above byother configurations that continue or terminate the extension of corematerial. In still other embodiment variations multiple continuingextension regions may be formed on a given layer for a given structure.

FIG. 10A provides a flowchart for forming a structure according to thesixth embodiment of the invention wherein a structure is formed with atleast one layer that includes a shell and core where the core extendsfrom the bottom of the layer to the top of the layer with shell wallssurrounding the sides of the core and wherein the shell walls may benarrower than a minimum feature size associated with the formation ofthe layer.

Like the other embodiments some of the steps of the embodiment of FIG.10A are similar to those of the previous embodiments and are labeledwith similar numbers with the exception that the series number startswith 600 instead of 100-500. In particular, steps 651-655 and 680-685are similar to the corresponding steps in the earlier embodiments withthe exception that the enquiry of step 654 is concerned about whetherthe current layer “n” is to be formed with a continuing shell instead ofa down-facing or up-facing shell material. However as compared to theembodiment of FIG. 9A all process steps are similar with exception ofsteps 669 and 670. Step 669 deposits the core structural material to aheight at least as great as the intended thickness of layer “n” whilestep 670 optionally planarizes the deposited core material to a heightat, and preferably somewhat above, the boundary level for the currentlayer “n

FIGS. 10B-10J illustrate various states of the process of FIG. 10A asapplied to the formation of a particular sample layer of a structurewhich has a configuration similar to that of a previous layer on whichit is formed with the exception that the previous layer was formed usingan up-facing shell and core method (such as that used in one of thefirst-fourth embodiments) and such that the core for the current layer“n” is formed starting in and extending from an immediately precedinglayer and extending into and through the current layer.

FIG. 10B shows the state of the process after a previously formed layerL(n−1) containing a shell region of a structural material 606, a coreregion of a structural material 612, and region of sacrificial material604 is provided with a photoresist 603-1 that is patterned to form amask with voids into which a current layer “n” of core structuralmaterial, e.g. functional structural material, may be deposited.

FIG. 10C shows the state of the process after the core structuralmaterial 612 is deposited to a height greater or equal to a desiredheight for the current layer “n” in anticipation of one or moresubsequent planarizations that will bring the effective height down to alevel equal to the boundary level for the current layer (i.e. within adesired tolerance of the upper boundary level for the current layer). Insome variations of this embodiment, the height of deposit of the corematerial may be set to the desired height which may eliminate the needfor a subsequent planarization process.

FIG. 10D depicts the state of the process after the structural material612 and the photoresist 603-1 of the current layer “n” are optionallyplanarized to a desired height which is at, or more preferably somewhatabove, the upper boundary level of the current layer so as to ensurethat in the presence of any tolerance errors, the core material willstill extend to the final upper boundary level.

FIG. 10E shows the state of the process after the photoresist 603-1 isstripped.

FIG. 10F shows the state of the process after additional photoresist603-2 is applied and patterned to form a void containing the corematerial and a surrounding void where a genuine structural material 606may be deposited to form the walls of the shell for the current layer“n”.

FIG. 10G shows the state of the process after deposition of the genuinestructural material 606 to a height that forms walls around the corestructural material 612 and forms a temporary cap over the core material612.

FIG. 10H shows the state of the process after the photoresist 603-2 isstripped in preparation for depositing a sacrificial material. In somevariations of this embodiment, the deposited structural material 606 maybe planarized before removal of the photoresist but this is generallynot considered necessary as it will undergo subsequent planarizationanyway.

FIG. 10I shows the state of the process after deposition of asacrificial material 604 raises the net height of material for allregions of the current layer “n” to at least the desired boundary heightor level of the current layer “n”.

FIG. 10J shows the state of the process after the sacrificial material604 the shell structural material 606 and the core structural material612 have been planarized to a height corresponds to the boundary levelof the current layer (i.e. in practice this will probably actually be alevel that is within a desired tolerance of the boundary level of thecurrent layer “n”). This step completes the formation of the currentlayer “n” and the structure can either proceed to post layer formationoperations if the just formed layer “n” was the last layer of thestructure or can have additional layers added on it if it was not thelast layer. As can be seen in this figure, the core material 612 extendsfrom the bottom of layer “n” to the top of layer “n” and is surroundedon the sides by shell material 606. It is clear that the core regionassociated with this layer may begin or end with this layer or maycontinue from one or more previous layers (as illustrated it started inthe middle of the previous layer) and/or continue into one or moresubsequent layers depending on the configuration of those previous andsubsequent layers and depending on the types of shell/core ornon-shell/core processes used in forming those previous and subsequentlayers.

As with the other embodiments discussed above numerous variations ofthis process are possible and include, for example, variations thatincorporate additional materials into shell/core layers, variations thatadd additional materials to non-shell/core layers, variations thatmodify the layer thickness between shell/core layers and non-shell/corelayers, variations that have more layers as many as 10, 20, 40 or evenmore, variations that use a non-conductive core material (that may becoated with a seed layer to allow deposition of additional layersaccording to the methods set forth in some of the patents andapplications incorporated herein by reference, variations that include aconductive core material and a non-conductive shell material on at leastsome layers, variations that leave the formed structure attached to thebuild substrate or to a different substrate that is attached, variationsthat extend core material to more than one layer when allowed by thegeometry of the structure being formed, variations that form some layersof some structures with more than one shell/core region, variations thatreverse the order of structural material and sacrificial materialdeposition on at least some layers, variations that use a non-conductivesacrificial material, variations that mix the shell/core formationmethod of another embodiment with those of this embodiment, and thelike. Additional variations will be understood by those of skill in theart upon review of the teachings herein.

In some variations of the first-sixth embodiments the wall thickness orwidth may be determined as a percentage of layer thickness, e.g. 10%,20%, 50%, 75%, or some other value. Assuming that wall width growth isrelated to base thickness build up during deposition, the base thicknessbuild up may be used to control the wall thickness with the basethickness for example being set to a faction of the layer thickness suchas 1/10, ⅕, ½, ¾, or any other fraction amount less than one. In someembodiments, base thickness and associated wall thickness may be set toa desired value instead of to a fraction of a layer thickness, such as abase thickness of 1, 2, 5, 10, 15 microns or some other appropriateamount that is less than a thickness of the layer being formed. Similarpercentages, fractions and thickness are also applicable to caps andcapping layers that might be formed in association with some layers.

Additional embodiments of the invention are possible. Some suchembodiments may result from the combination of various features of thefirst-sixth embodiments. For example, the teachings of the fourth-sixthembodiments may be combined to yield encapsulated core materialextending unbroken through any desired number of layers wherein aninitial layer is formed using the up-facing shelling method of thefourth embodiment, one or more intermediate layers are formed using thecontinuing encapsulation method of the sixth embodiment, and a finallayer provides for encapsulation using a down-facing shelling method asset forth in the fifth embodiment.

Other such alternative embodiments may result from combining theteachings of any one of the first-sixth embodiments with teachings fromthe various patents and applications incorporated herein by reference.For example during the formation of one or more layers of a structureusing one or more of the methods of the first-sixth embodiments one ormore of the stress reductions methods set forth in U.S. patentapplication Ser. No. 11/733,195, filed Apr. 9, 2007, now abandoned, andentitled “Methods of Forming Three-Dimensional Structures Having ReducedStress and/or Curvature” may be incorporated into the process. Asanother example, where probes or other structures (e.g. probes forperforming wafer level testing or burn-in of semiconductor devices) arebeing formed it may be desirable to have a contact tip element, or otherfeature, formed from a different material (e.g. rhodium) than used for abody of the probe or structure. In such cases the tip formation methodsas set forth in FIGS. 20A-20C and 21A-21E of the '195 patent applicationmay be combined with the methods of any of the first to sixthembodiments set forth herein with or without incorporating the stressreductions methods set forth therein.

In still other embodiment variations, other alternative methods, may beused to provide for complete encapsulation with general layer-to-layerinterfaces existing in the structure. In still other embodiments, suchgeneralized encapsulation may be possible without necessarilyencapsulating every layer individually but instead allowing corematerial to extend between successive layers when desired and whenallowed by geometric constraints that are associated with layer-to-layeroverlap requirements of a shelling material. Such alternativeembodiments, may use Boolean layer comparison operations (e.g. unions,intersections, and subtractions) to identify up-facing, continuing, anddown-facing regions of individual layers and possibly the use of erosionroutines and the like, potentially, in combination with Booleancomparisons to determine region widths and to derive lateral extensionsof such down-facing, continuing, or up-facing regions and more so todetermine what regions require special depositions of genuine structuralmaterial to form cap or cap portions and/or to avoid formation of suchcaps where continuation of core material is possible. For example, in asituation where it is known that a wall width, or thickness, of shellmaterial of 15 microns exists and that a minimum wall width, orthickness, of shell material of at least 5 microns is required, and itis found that a higher or lower layer has region boundaries that are nomore than 10 microns offset relative to the region boundaries of thecurrent layer, the up-facing, down-facing, or continuing shell/corematerial embodiments of the fourth to sixth embodiments may be usedwithout variation. However, if an offset of greater than 10 micronsexists and the offset includes a region of core material, an additionalor modified deposition of shelling material may be required to ensurefull encapsulation. In fact, if the offset is greater than both 10microns and a minimum feature size, an additional relatively thindeposition may be made using a mask corresponding to the offset regionin combination with the appropriate steps of the fourth to sixthembodiment. On the other hand, if the offset is between 10 microns andthe minimum feature size it may be necessary to either form a cappinglayer corresponding to the configuration of the entire layer having theoffset (assuming it is the layer with the offset that would otherwisecontain exposed core material) or to create and use a mask having arevised deposition region that can be defined by a mask that doesn'thave features less than the minimum feature size.

In the most preferred implementations of the present invention, thoughnot necessarily all implementations, structures will not be formed oneat a time but instead in batch processes that may build up tens,hundreds, or even thousands of identical or differing structuressimultaneously as each successive layer is formed on and adhered topreviously formed layers where the only requirements are that (1) thelayer levels be sufficiently compatible for each structure to allowsimultaneous build up and (2) associated coring/shelling operations arecompatible. In some embodiments, layers or groups of layers may beformed separate from other layers, or groups of layers, and then theseparate layers or groups aligned and bonded to one another to formcomplete structures.

FURTHER COMMENTS AND CONCLUSIONS

Various other embodiments of the present invention exist. Some of theseembodiments may be based on a combination of the teachings herein withvarious teachings incorporated herein by reference. For example someembodiments may not use any blanket deposition process. Some embodimentsmay use selective deposition processes or blanket deposition processeson some layers that are not electrodeposition processes. Someembodiments may use nickel as a structural material while otherembodiments may use different materials. For example, preferred springmaterials include nickel (Ni), copper (Cu), beryllium copper (BeCu),nickel phosphorous (Ni—P), tungsten (W), aluminum copper (Al—Cu), steel,P7 alloy, palladium, molybdenum, manganese, brass, chrome, chromiumcopper (Cr—Cu), and combinations of these. Some embodiments may usecopper as the structural material with or without a sacrificialmaterial.

Some embodiments may apply the fabrication processes disclosed herein tothe production of microprobes while other embodiments may apply thesemethods in the fabrication of other devices for other applications.

Some embodiments may employ diffusion bonding or the like to enhanceadhesion between successive layers of material. Various teachingsconcerning the use of diffusion bonding in electrochemical fabricationprocesses are set forth in U.S. patent application Ser. No. 10/841,384,which was filed May 7, 2004, by Cohen et al. now abandoned, which isentitled “Method of Electrochemically Fabricating Multilayer StructuresHaving Improved Interlayer Adhesion” and which is hereby incorporatedherein by reference as if set forth in full. This application is herebyincorporated herein by reference as if set forth in full.

Further teaching about microprobes and electrochemical fabricationtechniques are set forth in a number of prior US patent applications.These Filings include: (1) U.S. patent application Ser. No. 10/949,738(P-US119-A-MF), filed Sep. 24, 2004, by Kruglick et al., now abandoned,and which is entitled “Electrochemically Fabricated Microprobes”; (2)U.S. patent application Ser. No. 11/028,945 (P-US134-A-MF), filed Jan.3, 2005, by Cohen et al., now U.S. Pat. No. 7,640,651, and which isentitled “A Fabrication Method for Co-Fabricating a Probe Array and aSpace Transformers”. (3) U.S. patent application Ser. No. 11/029,180,filed Jan. 3, 2005, by Chen et al., now abandoned, and entitled“Pin-Type Probes for Contacting Electronic Circuits and Methods forMaking Such Probes”; (4) U.S. patent application Ser. No. 11/325,404(P-US153-A-MF), filed Jan. 3, 2005, by Chen et al., now abandoned, andentitled “Vertical Microprobes for Contacting Electronic Components andMethod for Making Such Probes”; (5) U.S. patent application Ser. No.11/029,217 (P-US122-A-MF), filed Jan. 3, 2005, by Kim et al., now U.S.Pat. No. 7,412,767, and entitled “Microprobe Tips and Methods ForMaking; and (6) U.S. patent application Ser. No. 11/173,241(P-US137-A-MF), filed Jun. 30, 2005, by Kumar et al., now abandoned, andentitled “Probe Arrays and Methods for Making”. These patent filings areeach hereby incorporated herein by reference as if set forth in fullherein.

Additional teachings concerning the formation of structures ondielectric substrates and/or the formation of structures thatincorporate dielectric materials into the formation process andpossibility into the final structures as formed are set forth in anumber of patent applications: (1) U.S. patent application Ser. No.11/028,957 (P-US127-A-SC), by Cohen, which was filed on Jan. 3, 2005,now abandoned, and which is entitled “Incorporating Dielectric Materialsand/or Using Dielectric Substrates”; (2) U.S. patent application Ser.No. 10/841,300 (P-US099-A-MF), by Lockard et al., which was filed on May7, 2004, now abandoned, and which is entitled “Methods forElectrochemically Fabricating Structures Using Adhered Masks,Incorporating Dielectric Sheets, and/or Seed Layers that are PartiallyRemoved Via Planarization”; (3) U.S. patent application Ser. No.10/841,378 (P-US106-A-MF), by Lembrikov et al., which was filed on May7, 2004, now U.S. Pat. No. 7,527,721, and which is entitled“Electrochemical Fabrication Method for Producing Multi-layerThree-Dimensional Structures on a Porous Dielectric”; (4) U.S. patentapplication Ser. No. 11/029,216 (P-US128-A-MF), filed Jan. 3, 2005 byCohen et al., now abandoned, and entitled “Electrochemical FabricationMethods Incorporating Dielectric Materials and/or Using DielectricSubstrates”; and (5) U.S. patent application Ser. No. 11/325,405(P-US152-A-MF), filed Jan. 3, 2006 by Dennis R. Smalley, now abandoned,and entitled “Method of Forming Electrically Isolated Structures UsingThin Dielectric Coatings”. These patent filings are each herebyincorporated herein by reference as if set forth in full herein.

The patent applications and patents set forth below are herebyincorporated by reference herein as if set forth in full. The teachingsin these incorporated applications can be combined with the teachings ofthe instant application in many ways: For example, enhanced methods ofproducing structures may be derived from some combinations of teachingsand enhanced structures may be obtainable.

U.S. patent application Ser. No., Filing Date U.S. App Pub No., Pub DateU.S. Pat. No., Pub Date First Named Inventor, Title U.S. patentapplication Ser. No. 09/493,496 - Jan. 28, 2000 Cohen, “Method ForElectrochemical Fabrication” — U.S. Pat. No. 6,790,377 - Sep. 14, 2004U.S. patent application Ser. No. 10/607,931- Jun. 27, 2003 Brown,“Miniature RF and Microwave Components and 2004-0140862 - Jul. 22, 2004Methods for Fabricating Such Components” U.S. Pat. No. 7,239,219 - Jul.3, 2007 U.S. patent application Ser. No. 10/434,295 - May 7, 2003 Cohen,“Method of and Apparatus for Forming Three- 2004-0004001A - Jan. 8, 2004Dimensional Structures Integral With Semiconductor Lapsed BasedCircuitry” U.S. patent application Ser. No. 10/841,006 - May 7, 2004Thompson, “Electrochemically Fabricated Structures 2005-0067292 - May31, 2005 Having Dielectric or Active Bases and Methods of and LapsedApparatus for Producing Such Structures” U.S. patent application Ser.No. 10/434,519 - May 7, 2003 Smalley, “Methods of and Apparatus for2004-0007470A - Jan. 15, 2004 Electrochemically Fabricating StructuresVia Interlaced U.S. Pat. No. 7,252,861 - Aug. 7, 2007 Layers or ViaSelective Etching and Filling of Voids” U.S. patent application Ser. No.10/841,347 - May 7, 2004 Cohen, “Multi-step Release Method forElectrochemically 2005-0072681 - Apr. 7, 2005 Fabricated Structures”Lapsed U.S. patent application Ser. No. 11/733,195 - Apr. 9, 2007 Kumar,“Methods of Forming Three-Dimensional 2008-0050524 - Feb. 28, 2008Structures Having Reduced Stress and/or Curvature” Lapsed U.S. patentapplication Ser. No. 10/949,744 - Sep. 24, 2004 Lockard,“Three-Dimensional Structures Having Feature 2005-0126916 - Jun. 16,2005 Sizes Smaller Than a Minimum Feature Size and U.S. Pat. No.7,498,714 - Mar. 3, 2009 Methods for Fabricating”

Though various portions of this specification have been provided withheaders, it is not intended that the headers be used to limit theapplication of teachings found in one portion of the specification fromapplying to other portions of the specification. For example, it shouldbe understood that alternatives acknowledged in association with oneembodiment, are intended to apply to all embodiments to the extent thatthe features of the different embodiments make such applicationfunctional and do not otherwise contradict or remove all benefits of theadopted embodiment. Various other embodiments of the present inventionexist. Some of these embodiments may be based on a combination of theteachings set forth herein with various teachings incorporated herein byreference.

In view of the teachings herein, many further embodiments, alternativesin design and uses of the embodiments of the instant invention will beapparent to those of skill in the art. As such, it is not intended thatthe invention be limited to the particular illustrative embodiments,alternatives, and uses described above but instead that it be solelylimited by the claims presented hereafter.

We claim:
 1. A compliant probe comprising: a) a first planarized layercomprising at least a first structural material and a second structuralmaterial located above at least a portion of the first structuralmaterial wherein at least the second structural material is planarizedto set a boundary level for the first planarized layer; b) a secondplanarized layer comprising at least a third structural material,wherein the third structural material is either directly adhered to amaterial selected from the group consisting of the first structuralmaterial of the first planarized layer, the second structural materialof the first planarized layer, and a material of an intermediate layerthat separates the first planarized layer from the second planarizedlayer; wherein the second structural material of the first planarizedlayer is different from both the first structural material of the firstplanarized layer and the third structural material of the secondplanarized layer, wherein the second structural material of the firstplanarized layer has sides, and wherein at least a portion of the sidesof the second structural material of the first planarized layer arebounded by the first structural material of the first planarized layer,and wherein the first, second, and third structural materials aremetals; wherein upon use, the compliant probe is configured to providean electrical contact with an integrated circuit.
 2. The compliant probeof claim 1 wherein the first structural material of the first planarizedlayer and third structural material of the second planarized layer arethe same material.
 3. The compliant probe of claim 2 wherein at leastone of the materials selected from the group consisting of (1) the firststructural material, (2) the second structural material, and (3) thethird structural material comprises a material selected from the groupconsisting of: (1) nickel (Ni), (2) copper (Cu), (3) beryllium copper(BeCu), (4) nickel phosphor (Ni—P), (5) tungsten (W), (6) aluminumcopper (Al—Cu), (7) steel, (8) P7 alloy, (9) palladium, (10) molybdenum,(11) manganese, (12) brass, (13) chrome, (14) chromium copper (Cr—Cu),(15) gold (Au), (16) silver (AG), (17) nickel-cobalt (Ni—Co), (18)palladium-cobalt (Pd—Co), (19) tin (Sn), and (20) a combination of anytwo of these materials.
 4. The compliant probe of claim 1 additionallycomprising a contact tip material forming part of at least one layerselected from the group consisting of the first planarized layer, theintermediate layer, and the second planarized layer.
 5. The compliantprobe of claim 4 wherein the contact tip material is different fromanother structural material forming part of the same layer.
 6. Thecompliant probe of claim 5 wherein the at least one layer that comprisesthe contact tip also comprises a core material that is different fromboth the contact tip material and another structural material of thesame layer.
 7. The compliant probe of claim 5 wherein in the contact tipcomprises rhodium.
 8. The compliant probe of claim 1 wherein acompressive direction of the probe is perpendicular to a direction ofstacking of the first and second planarized layers.
 9. The compliantprobe of claim 1 wherein a compressive direction of the probe issubstantially parallel to a stacking direction of the first and secondplanarized layers.
 10. The compliant probe of claim 1 wherein the firstand third structural materials have a higher yield strength than thesecond structural material.
 11. The compliant probe of claim 1 whereinthe second structural material has a higher electrical conductive thanthe first and third structural materials.
 12. The compliant probe ofclaim 1 wherein the second structural material is fully encapsulated bya different structural material.
 13. The compliant probe of claim 1wherein the first, second, and third structural materials areelectrodeposited materials.
 14. A compliant probe for providing anelectrical connection between at least two electronic components, theprobe comprising: a) a first planarized layer comprising at least afirst structural material; b) a second planarized layer comprising atleast a second structural material, wherein the second structuralmaterial of the second planarized layer has a relationship with thefirst planarized layer selected from the group consisting of: (1) thesecond structural material of the second planarized layer is directlyadhered to the first planarized layer, (2) the second structuralmaterial or the second planarized layer is separated from the firstplanarized layer by at least one intermediate layer, and (3) the secondstructural material of the second planarized layer is separated from thefirst planarized layer by at least one deposition of material; c) athird planarized layer comprising at least a third structural material,wherein the third structural material of the third planarized layer hasa relationship with the second planarized layer selected from the groupconsisting of: (1) the third structural material of the third planarizedlayer is adhered directly to the second planarized layer, (2) the thirdstructural material of the third planarized layer is separated from thesecond planarized layer by at least one intermediate layer, and (3) thethird structural material of the third planarized layer is separatedfrom the second planarized layer by at least one deposition of material,wherein the second planarized layer is located between the first andthird planarized layers, and wherein the second structural material isdifferent from both the first structural material and the thirdstructural material, and wherein the compliant probe is configured toprovide a compliant electrical contact element that provides aconductive path between the at least two electronic components, whereineach of at least one of the first to third planarized layers comprisesat least one core structural material and at least one shell structuralmaterial, wherein one of the at least one core structural material andthe at least one shell structural material of a respective layercorresponds to a respective first structural material, second structuralmaterial, or third structural material while another of the at least oneshell structural material and at least one core structural material donot, and wherein the shell structural material of the respective layersurrounds a bottom and sides of at least selected volumes of the corestructural material of the respective layer.
 15. The compliant probe ofclaim 14 wherein the respective layer comprises the second planarizedlayer and at least one core structural material comprises the secondstructural material of the second planarized layer and at least oneshell structural material of the second planarized layer comprises adifferent material.
 16. The compliant probe of claim 15 wherein thefirst and third structural materials and the at least one shellstructural material of the second planarized layer comprise the samematerial.
 17. The compliant probe of claim 16 wherein at least one ofthe materials selected from the group consisting of (1) the firststructural material, (2) the second structural material, and (3) thethird structural material comprises a material selected from the groupconsisting of: (1) nickel (Ni), (2) copper (Cu), (3) beryllium copper(BeCu), (4) nickel phosphor (Ni—P), (5) tungsten (W), (6) aluminumcopper (Al—Cu), (7) steel, (8) P7 alloy, (9) palladium, (10) molybdenum,(11) manganese, (12) brass, (13) chrome, (14) chromium copper (Cr—Cu),(15) gold (Au), (16) silver (AG), (17) nickel-cobalt (Ni—Co), (18)palladium-cobalt (Pd—Co), (19) tin (Sn), and (20) a combination of anytwo of these materials.
 18. The compliant probe of claim 14 additionallycomprising a contact tip material forming part of at least one layerwherein the contact tip material is a different metal than that of theat least one core structural material.
 19. The compliant probe of claim18 wherein the contact tip material of a layer is different from anotherstructural material forming part of the same layer.
 20. The compliantprobe of claim 14 wherein at least two of the first, second, and thirdplanarized layers comprise regions of core materials and shellmaterials.